ASSIGMENT DISCUSSION

The purpose of this Biology Discussion is to help each other understand the main concepts presented in the chapters covered this week. General Biology, the required readings are Chapters 4 -7.

*One of the entries MUST ask a question about a concept/idea presented in the required readings in the textbook from the chapters covered this week. This should be a question pertaining to material that you personally do not understand or need clarification on and should be at least 40-50 words in length. Question topics cannot be claimed, and it is one question topic per student. This will aid in diversifying the discussion. Broad categories are posted already in the discussion board. Post your question under the category to which it best applies. State your question in the subject line of the post. This will create a list of questions and that everyone will be able to see.

2 Biology Discussion

The purpose of this Biology Discussion is to help each other understand the main concepts presented in the chapters covered this week. General Biology, the required readings are Chapters 4 -7.

Each student must make at least three (3) entries during the week. *One of the entries MUST ask a question about a concept/idea presented in the required readings in the textbook from the chapters covered this week . This should be a question pertaining to material that you personally do not understand or need clarification on and should be at least 40-50 words in length. Question topics cannot be claimed, and it is one question topic per student. This will aid in diversifying the discussion. Broad categories are posted already in the discussion board. Post your question under the category to which it best applies. State your question in the subject line of the post. This will create a list of questions and that everyone will be able to see. *The two remaining entries must offer an explanation in answer to a classmate's question. Your responses must be researched, and the content of your response must be supported by reliable and credible resources. These two response posts must be a minimum of 200 words each. *Ground rules for the Biology Discussion: Each post must be in your own words. Do NOT copy and paste from the Internet. [Review the Plagiarism presentation in the Student Resource Center.] It is better to paraphrase content/information (putting the content/information in your own words) from a resource. Paraphrased information from resource is required to be properly cited per APA requirements*, with it-text citations immediately following the information and a full reference citation at the end of the discussion board posting. [*Refer to the Getting Started area of the class for ‘Helpful Resources & Websites on Referencing Sources per APA’ and to the Student Resources tab on the left-hand side of the classroom.]

Chapter 7

Energy for Cells

Essentials of Biology

SEVENTH EDITION

Sylvia S. Mader Michael Windelspecht

Because learning changes everything.®

7.1 Cellular Respiration

Produces ATP molecules for energy

Requires oxygen and glucose; produces carbon dioxide and water

Reason you breathe

Essentially the reverse of photosynthesis

Figure 7.1 Cellular Respiration

Access the text alternative for slide images.

(photo): Juice Dash/Shutterstock

Glucose Is Broken Down in Steps

Phases of complete glucose breakdown

Glucose broken down slowly in steps

Allows energy to be captured and used to make ATP

Coenzymes (nonprotein helpers) join with hydrogen

N A D⁺ → NADH

F A D⁺→ FADH2

Cellular Respiration Involves Redox Reactions

Oxidation = removal of hydrogen atoms

Hydrogens removed from glucose

Gives waste product carbon dioxide

Reduction = addition of hydrogen atoms

Oxygen accepts hydrogens

Become waste product water

Access the text alternative for slide images.

Figure 7.3 The Four Phases of Complete Glucose Breakdown

Access the text alternative for slide images.

7.2 Outside the Mitochondria: Glycolysis

Glycolysis

In eukaryotes, takes place in the cytoplasm

Glucose (six carbons) broken down into two molecules of pyruvate (three carbons)

Divided into:

Energy-investment steps

Energy-harvesting steps

Access the text alternative for slide images.

Figure 7.4 Glycolysis, Energy-Investment Step

The following content is arranged like a table.

3PG 3-phosphoglycerate

BPG 1,3-bisphosphoglycerate

G3P glyceraldehyde 3-phosphate

Energy-investment steps

Two ATP transfer phosphates to glucose

Activates them for next steps

Access the text alternative for slide images.

Figure 7.4 Glycolysis, Energy-Harvesting Steps

Energy-harvesting steps

Substrate-level ATP synthesis produces four ATP

Net gain of two ATP

Two NADH made

The following content is arranged like a table.

3PG 3-phosphoglycerate

BPG 1,3-bisphosphoglycerate

G3P glyceraldehyde 3-phosphate

Return to parent-slide containing images.

Figure 7.6 Glycolysis Totals

Next step depends on oxygen availability.

With oxygen, pyruvate enters mitochondria.

Without oxygen, pyruvate undergoes reduction.

Access the text alternative for slide images.

7.3 Outside the Mitochondria: Fermentation 1

Oxygen is required for the complete breakdown of glucose in aerobic respiration.

Fermentation—anaerobic breakdown of glucose

Generates only two ATP total

Animal cells

Pyruvate reduced to lactate

Brief burst of energy for muscle cells

Recovery from oxygen deficit complete when enough oxygen is present to completely break down glucose

Lactate converted back to pyruvate or glucose

Outside the Mitochondria: Fermentation 2

Microorganisms and fermentation

Bacteria use fermentation to produce:

Lactate or other organic acids

Alcohol and carbon dioxide

Yeast—carbon dioxide makes bread rise, ethanol made into wine and beer

Access the text alternative for slide images.

Figure 7.7 The Anaerobic Pathways, Glycolysis 1

Access the text alternative for slide images.

Figure 7.7 The Anaerobic Pathways 2

Access the text alternative for slide images.

(runner): Michael Svoboda/iStockphoto/Getty Images; (wine): C Squared Studios/Photodisc/Getty Images

Figure 7.7 The Anaerobic Pathways 3

Access the text alternative for slide images.

(runner): Michael Svoboda/iStockphoto/Getty Images; (wine): C Squared Studios/Photodisc/Getty Images

7.4 Inside the Mitochondria

Access the text alternative for slide images.

Keith R. Porter/Science Source

Inside the Mitochondria, Preparatory Reaction

Preparatory reaction

Occurs in mitochondrial matrix

Produces a substrate that enters the citric acid cycle

Occurs twice per glucose molecule

Pyruvate oxidized, C O2 molecule given off

N A D⁺ →NADH

2-carbon acetyl group attached to CoA to form acetyl-CoA

Inside the Mitochondria, Citric Acid Cycle

Citric Acid Cycle

Occurs in matrix of mitochondria

Acetyl CoA transfer acetyl group to C4 molecule—produces citric acid (six carbons)

CoA returns to preparatory reaction for reuse

Acetyl group oxidized to carbon dioxide

N A D⁺ →NADH and F A D →FADH2

Substrate-level ATP synthesis produces ATP

Two cycles for each glucose molecule

The Preparatory Reaction

Access the text alternative for slide images.

The Citric Acid Cycle

Access the text alternative for slide images.

Figure 7.11 Inputs and Outputs of the Citric Acid Cycle

Access the text alternative for slide images.

Electron Transport Chain 1

Electron transport chain location

Located in cristae of mitochondria

Series of carriers pass electrons from one to the other

NADH and FADH2 deliver electrons

Hydrogen atoms attached consist of e⁻ and H²

Carriers accept only e⁻ not H²

Access the text alternative for slide images.

Electron Transport Chain 2

High-energy electrons enter/low-energy electrons leave

As pair of electrons passed from one carrier to the next, energy is released.

Will be captured for ATP production

Final electron acceptor is oxygen—forms water.

Access the text alternative for slide images.

Figure 7.13a The Electron Transport Chain

Access the text alternative for slide images.

ATP Synthase

ATP synthesis carried out by ATP synthase in inner mitochondrial membrane

Carriers of electron transport system pass electrons

Energy used to pump H⁺ from matrix into intermembrane space—creates H⁺ gradient

ATP synthase uses energy to make ATP.

Figure 7.13b

Access the text alternative for slide images.

Figure 7.13 The Organization of Cristae

Orange arrow indicates flow of electrons through carriers in ETC

H⁺ ions accumulate in intermembrane space and are then used to in the ATP synthase complex to form ATP.

Access the text alternative for slide images.

7.5 Metabolic Fate of Food

Energy yield from glucose metabolism

Maximum of 38 ATP made

Some cells make only 36 ATPs or less.

36–38 ATP about 40% of available energy in a glucose molecule

Rest is lost as heat.

Access the text alternative for slide images.

Alternative Metabolic Pathways, Fats and Proteins

Cells use other energy sources such as proteins and fats.

Fatty acids have longer carbon chains—yields more ATP.

Intermediates can also be used to make other products.

Extra food made into fat for storage.

Access the text alternative for slide images.

(photo): C Squared Studios/Photodisc/Getty Images

End of Main Content

Because learning changes everything.®

www.mheducation.com

Accessibility Content: Text Alternatives for Images

Figure 7.1 Cellular Respiration – Text Alternative

Return to parent-slide containing images.

The respiration process involves intake of oxygen and glucose and the release of carbon dioxide and water which takes place in the mitochondrion. The mitochondrion has a double membrane (inner and outer membranes), matrix, cristae, and intermembrane space.

Return to parent-slide containing images.

Cellular Respiration Involves Redox Reactions – Text Alternative

Return to parent-slide containing images.

In the reaction, glucose combines with six molecules of oxygen giving six molecules of carbon dioxide, six molecules of water, and energy. Both oxidation and reduction occur during cellular respiration. The glucose molecule is oxidized to produce carbon dioxide and oxygen molecules are reduced to generate water molecules.

Return to parent-slide containing images.

Figure 7.3 The Four Phases of Complete Glucose Breakdown – Text Alternative

Return to parent-slide containing images.

The first stage of cellular respiration is glycolysis in which a glucose molecule breaks down into pyruvate. Glycolysis occurs in the cytoplasm of the cell. The net gain of ATP in glycolysis is 2ATP. The pyruvate enters into mitochondria and undergoes a preparatory reaction. C O2 is produced in the reaction. Further, the products of the preparatory phase undergo a citric acid cycle reaction during which 2ATP and C O2 are produced. The last step is the electron transport chain. During the process, the carrier molecule NADH transfers electrons from the original glucose molecule to an electron transport chain. In this way, the electrons move within the inner membrane of the mitochondria by NADH and FADH2, ultimately being pulled to oxygen found at the end of the chain. The oxygen and electrons combine with hydrogen ions to form water. This step generates 34 ATP molecules.

Return to parent-slide containing images.

7.2 Outside the Mitochondria: Glycolysis – Text Alternative

Return to parent-slide containing images.

The first stage of cellular respiration is glycolysis in which a glucose molecule breaks down into pyruvate. Glycolysis occurs in the cytoplasm of the cell. The net gain of ATP in glycolysis is 2ATP. The pyruvate enters into mitochondria and undergoes a preparatory reaction. Further, the products of the preparatory phase undergo citric acid reaction during which 2ATP are produced. The last step of cellular respiration is the electron transport chain. During the process, the carrier molecule NADH transfers electrons from the original glucose molecule to an electron transport chain. In this way, the electrons move within the inner membrane of the mitochondria by NADH and FADH2. This step generates 34 ATP molecules.

Return to parent-slide containing images.

Figure 7.4 Glycolysis, Energy-Investment Step – Text Alternative

Return to parent-slide containing images.

Energy-investment step:

Six carbon glucose on the conversion of two ATP molecules into two ADP molecules forms a chain of two 3-carbon glyceraldehyde 3-phosphate (G3P) molecules linked together. Further, the chain of two glyceraldehyde 3-phosphate molecules bifurcates into two molecules of glyceraldehyde 3-phosphate.

Return to parent-slide containing images.

Figure 7.4 Glycolysis, Energy-Harvesting Steps – Text Alternative

Return to parent-slide containing images.

Right Top: Step 1: energy investment step: glucose is broken down to ADP and P which is converted to G3P and P. Step 2: energy-harvesting steps: G3P is converted to BPG, while N A D superscript positive is converted to NADH in the presence of P. BPG is converted to 3PG, while ADP is converted to ATP. 3PG is converted to water and P which is converted to pyruvate. Net gain: 2 ATP.

Left Bottom: In the reaction, the reactant shows a chain of three spheres having first and third spheres linked with two phosphate groups each. The bond of the first phosphate group is marked as substrate. The phosphate group attached to the third sphere binds to an enzyme and on the conversion of ADP into ATP gives the product as a chain of three spheres with the first sphere linked to a phosphate group. A dotted curvy arrow shows the linking of the phosphate group to the ADP molecule.

Return to parent-slide containing images.

Figure 7.6 Glycolysis Totals – Text Alternative

Return to parent-slide containing images.

The inputs of glycolysis include glucose, two molecules of N A D plus, two molecules of ATP, four molecules of ADP, and two Phosphates. The outputs include two molecules of pyruvate, two molecules of NADH, two molecules of ADP, and four molecules of ATP. The net gain is shown as two molecules of ATP.

Return to parent-slide containing images.

Outside the Mitochondria: Fermentation 2 – Text Alternative

Return to parent-slide containing images.

The inputs of fermentation include glucose, two molecules of NADH, two molecules of ATP, four molecules of ADP, and four Phosphates. The outputs include two molecules of lactate or two molecules of alcohol and two molecules of carbon dioxide, two molecules of N A D plus, two molecules of ADP, and four molecules of ATP. The process of fermentation shows a net gain of two molecules of ATP.

Return to parent-slide containing images.

Figure 7.7 The Anaerobic Pathways, Glycolysis 1 – Text Alternative

Return to parent-slide containing images.

The steps are as follows:

1. A 6-carbon glucose molecule converts into two molecules of a 3-carbon compound attached with a phosphate group at one end. Two molecules of ATP break into ADP with a net loss of two molecules of ATP.

2. Two molecules of a 3-carbon compound on the addition of two molecules of phosphate and conversion of two N A D positive into two NADH forms two molecules of another 3-carbon compound attached with phosphate groups at both ends.

3. Further, the 3-carbon compound on the conversion of four molecules of ADP into four molecules of ATP forms two molecules of pyruvate.

Return to parent-slide containing images.

Figure 7.7 The Anaerobic Pathways 2 – Text Alternative

Return to parent-slide containing images.

In fermentation, two molecules of pyruvate form either two molecules of lactate or two molecules of alcohol. The formation of lactate during fermentation is called lactic acid fermentation (exemplified by a photo of a woman in activewear bent down with her hands on her knees). The formation of alcohol during fermentation is called alcohol fermentation (exemplified by a photo of an alcohol bottle). If alcohol is formed, then the conversion of two NADH taken from glycolysis converts into two N A D positive, and two molecules of carbon dioxide are given out. The net gain of the process is 2 ATP.

Return to parent-slide containing images.

Figure 7.7 The Anaerobic Pathways 3 – Text Alternative

Return to parent-slide containing images.

The steps are as follows:

Glycolysis:

3. Further, the 3-carbon compound on the conversion of four molecules of ADP into four molecules of ATP forms two molecules of pyruvate depicting a net gain of four molecules of ATP.

Fermentation:

1. In fermentation, two molecules of pyruvate form either two molecules of lactate or two molecules of alcohol. The formation of lactate during fermentation is called lactic acid fermentation while the formation of alcohol during fermentation is called alcohol fermentation. If alcohol is formed then the conversion of two NADH taken from glycolysis converts into two N A D positive and two molecules of carbon dioxide are given out. The net gain of the process is 2 ATP.

Return to parent-slide containing images.

7.4 Inside the Mitochondria – Text Alternative

Return to parent-slide containing images.

A micrograph of mitochondrion and a drawing of the same shows outer membrane, matrix, cristae, and inner membrane space. Cristae: location of the electron transport chain, matrix: location of the prep reaction and the citric acid cycle, mitochondrion: location of aerobic respiration, cytoplasm: location of glycolysis.

Return to parent-slide containing images.

The Preparatory Reaction – Text Alternative

Return to parent-slide containing images.

The illustration shows how the preparatory reaction results in Citric acid cycle using NADH and FADH2, producing 2 ATPs in the matrix of a mitochondrion. The first stage of cellular respiration is glycolysis. The net gain of ATP in glycolysis is 2ATP. The pyruvate enters into mitochondria and undergoes a preparatory reaction. Further, the products of the preparatory phase undergo citric acid reaction during which 2ATP are produced. The last step of cellular respiration is the electron transport chain. During the process, the carrier molecule NADH transfers electrons from the original glucose molecule to an electron transport chain. In this way, the electrons move within the inner membrane of the mitochondria by NADH and FADH2. This step generates 34 ATP molecules.

Step 1 of the preparatory reaction: Each pyruvate from glycolysis is oxidized to a 2-carbon acetyl group that is carried by CoA to the citric acid cycle.

Return to parent-slide containing images.

The Citric Acid Cycle – Text Alternative

Return to parent-slide containing images.

The steps are as follows:

2) Each 2-carbon acetyl group combines with a 4-carbon molecule to produce citric acid, a 6-carbon molecule.

3) Oxidation reactions produce NADH, and C O2 is released.

4) The loss of two C O2 results in a new 4-carbon molecule.

5) ATP is produced by substrate-level ATP synthesis.

6) Additional oxidation reactions produce another NADH and an FADH2 and regenerate the original 4-carbon molecule.

Return to parent-slide containing images.

Figure 7.11 Inputs and Outputs of the Citric Acid Cycle – Text Alternative

Return to parent-slide containing images.

Inputs: 2 acetyl-C o A, 6 N A D superscript positive, 2 F A D, 2 ADP plus 2 P. Outputs: 4 C O2, 6 NADH, 2 FADH2, 2 ATP.

Return to parent-slide containing images.

Electron Transport Chain 1 – Text Alternative

Return to parent-slide containing images.

Cytoplasm:

Glucose undergoes glycolysis and forms two molecules of pyruvate with a net gain of two ATP. The two NADH plus hydrogen ion produced during glycolysis go through an electron transport chain and forms four or six ATP molecules.

Mitochondrion:

Two pyruvate converts into two acetyl coenzyme A with the release of two molecules of carbon dioxide. The two NADH plus hydrogen ion produced during the step go through the electron transport chain and form six ATP molecules.

The citric acid cycle releases four molecules of carbon dioxide. The six molecules of NADH plus hydrogen ion produced during citric acid go through the electron transport chain and produce eighteen ATP molecules. The citric acid cycle also produces two molecules of dihydro-flavin adenine dinucleotide which form four ATP molecules through the electron transport chain.

Six molecules of oxygen convert to six molecules of water.

A subtotal of four ATP obtained from the net gain of glycolysis and citric acid cycle with a subtotal of 32 or 34 ATP obtained from the electron transport chain gives out a total yield of 36 to 38 ATP.

Return to parent-slide containing images.

Electron Transport Chain 2 – Text Alternative

Return to parent-slide containing images.

Cytoplasm:

Mitochondrion:

Six molecules of oxygen convert to six molecules of water.

Return to parent-slide containing images.

Figure 7.13a The Electron Transport Chain – Text Alternative

Return to parent-slide containing images.

The cross-section of the mitochondrion shows three labeled parts including matrix, cristae, and intermembrane space. The enlarged view of intermembrane space and matrix shows the processes as follows:

a. Electron transport chain: The electron transport chain is a series of electron transporters carriers embedded in the inner mitochondrial membrane. Mobile carriers transport electrons from NADH and FADH2 to molecular oxygen. NADH produces N A D positive and FADH2 produces F A D. Hydrogen ions are pumped from the mitochondrial matrix to the intermembrane space, and oxygen is reduced to form water.

Return to parent-slide containing images.

ATP Synthase – Text Alternative

Return to parent-slide containing images.

b. ATP synthesis: The synthesis of ATP from ADP and phosphate is catalyzed by the ATP synthase complex, a mitochondrial enzyme located in the inner membrane. The synthesis of ATP is driven by the flow back of hydrogen ions across a gradient generated by the ATP synthase complex.

Return to parent-slide containing images.

Figure 7.13 The Organization of Cristae – Text Alternative

Return to parent-slide containing images.

a. Electron transport chain: The electron transport chain is a series of electron transporters carriers embedded in the inner mitochondrial membrane. Mobile carriers transport electrons from NADH and FADH2 to molecular oxygen. Hydrogen ions are pumped from the mitochondrial matrix to the intermembrane space, and oxygen is reduced to form water.

Return to parent-slide containing images.

7.5 Metabolic Fate of Food – Text Alternative

Return to parent-slide containing images.

The data given in the table are as follows:

Phase; Glycolysis, NADH; 2, FADH2; blank, ATP yield; 2

Phase; Prep reaction, NADH; 2, FADH2; blank, ATP yield; blank

Phase; Citric acid cycle, NADH; 6, FADH2; 2, ATP yield; 2

Phase; Electron transport chain, NADH; 10, FADH2; 2, ATP yield; 34

Total ATP; 38

Return to parent-slide containing images.

Alternative Metabolic Pathways, Fats and Proteins – Text Alternative

Return to parent-slide containing images.

Proteins: During respiration, proteins reversibly split into amino acids which further lose ammonia and undergo different steps including glycolysis, formation of acetyl co A and citric acid cycle. The products of the citric acid cycle undergo an electron transport chain. ATP is released during glycolysis, citric acid cycle, and electron transport chain.

Carbohydrates: Carbohydrates reversibly convert into glucose which goes through the further steps of respiration including glycolysis, formation of acetyl co A and citric acid cycle. The products of the citric acid cycle undergo an electron transport chain. Oxygen O2 is reduced to form water H2O via electron transport chain. ATP is released during glycolysis, citric acid cycle, and electron transport chain.

Fats: Fats break up into fatty acids and glycerol before being used in respiration. Fatty acids are broken into acetyl coenzyme A and then enter the citric acid cycle. Glycerol enters glycolysis and further steps of respiration. ATP is also released during the steps of fat respiration.

Return to parent-slide containing images.

image2.jpg

image3.png

image4.png

image5.png

image6.png

image7.png

image8.png

image9.png

image10.png

image11.png

image12.png

image13.png

image14.png

image15.png

image16.png

image17.png

image18.png

image19.png

image20.png

image21.png

image22.png

image23.png

image1.png

Chapter 5

The Dynamic Cell

Essentials of Biology

SEVENTH EDITION

Sylvia S. Mader Michael Windelspecht

Because learning changes everything.®

5.1 What Is Energy?

Energy is the capacity to do work.

Our biosphere gets its energy from the sun.

Two basic forms of energy

Potential energy—stored energy

Kinetic energy—energy of motion

Two forms are converted back and forth.

During conversions, some lost as heat.

Figure 5.1 Potential Energy Versus Kinetic Energy

Access the text alternative for slide images.

Calorie and Kilocalorie

Measuring energy

Food energy is measured in calories.

Calorie—amount of heat required to raise temperature of 1 g of water by 1°C

Kilocalorie or calorie = 1,000 calories

Value listed on food packages

Energy Laws

Two energy laws

First law—conservation of energy

Energy cannot be created or destroyed, but it can be changed from one form to another.

Second law

Energy cannot be changed from one form to another without a loss of usable energy.

Heat is the least usable form of energy.

Entropy 1

Entropy:

Every energy transformation leads to an increase in the amount of disorganization or disorder.

Entropy—relative amount of disorganization

Only way to maintain or bring about order is to add energy.

Entropy 2

Entropy, continued

Our universe is a closed system.

All energy transformations increase the total entropy of the universe.

Energy provided by the sun allows plants to make glucose from the more disorganized water and carbon dioxide.

Some of sun’s energy is lost as heat.

Figure 5.2a Cells and Entropy

Access the text alternative for slide images.

(photos: both): Keith Eng, 2008

Figure 5.2b Cells and Entropy

Unequal distribution of hydrogen ions

Equal distribution of hydrogen ions

5.2 ATP: Energy for Cells

Adenosine triphosphate (ATP)

Energy currency of cells

Cells use ATP to carry out nearly all activities.

One nucleotide along with three phosphate groups makes it unstable.

Easily loses a phosphate group to become adenosine diphosphate (ADP)

Continual cycle of breakdown and regeneration

Figure 5.3 ATP

Access the text alternative for slide images.

Figure 5.4 The ATP Cycle

ATP releases energy quickly.

Amount of energy released is usually just enough for a biological purpose.

Breakdown can be easily coupled to an energy-requiring reaction.

Access the text alternative for slide images.

Coupled Reactions

Coupled reactions:

Energy-releasing reaction can drive an energy-requiring reaction.

Usually, energy-releasing reaction is ATP breakdown.

Figure 5.5 Coupled Reaction

ATP breakdown provides the energy for muscle movement.

Myosin combines with ATP.

ATP breaks down.

Release of ADP + P causes myosin to change shape and pull on the actin filament.

Access the text alternative for slide images.

The Flow of Energy

The flow of energy:

Activities of chloroplasts and mitochondria enable energy to flow from the sun through all living things.

Photosynthesis—solar energy used to convert water and carbon dioxide into carbohydrates

Food for plants and other organisms

Cellular respiration—carbohydrates broken down and energy used to build ATP

Useful energy is lost with each transformation.

Living things dependent on constant in/out of solar energy

Figure 5.6 Flow of Energy

Access the text alternative for slide images.

(leaves): ooyoo/Getty Images; (woman): Karl Weatherly/Photodisc/Getty Images

Humans and Energy

Humans are also involved in the cycling of molecules between plants and animals and in the flow of energy from the sun.

Inhale oxygen, eat plants and animals

Energy rich foods allow us to produce the ATP required to maintain our bodies and carry on activities.

5.3 Metabolic Pathways and Enzymes

a. Active enzyme and active pathway

b. Feedback inhibition

c. Inactive enzyme and inactive pathway

Metabolic pathway—series of linked reactions

The letters

represent enzymes.

Protein molecules that function as organic catalysts speed up reactions.

Can only speed up possible reactions

Access the text alternative for slide images.

Figure 5.7 Enzymatic Action

Enzymes

Act on substrates

May facilitate breakdown or synthesis reactions

Enzyme’s Active Site

Enzyme’s active site

Accommodates substrate

Like a lock and key—specific to one substrate

Induced fit model—undergoes slight shape change to accommodate substrate

Change in shape facilitates reaction

Active site returns to original shape after releasing product(s)

Enzymes are not used up by the reaction.

Enzyme Inhibition

Enzyme inhibition:

Occurs when an active enzyme is prevented from combining with its substrate.

Cyanide is a poison because it binds to and inhibits cytochrome c oxidase.

Penicillin interferes with a bacterial enzyme that kills the bacteria.

Feedback inhibition

When a product is in abundance, it competes with substrate for active site

An end product of a pathway can inhibit the first enzyme in the pathway—binds to a site other than active site to cause shape change—which shuts the entire pathway down

Figure 5.8a Feedback Inhibition—Active Enzyme and Active Pathway

a. Active enzyme and active pathway

Access the text alternative for slide images.

Figure 5.8b Feedback Inhibition

b. Feedback inhibition

When a product builds up—the body doesn’t need more

Product binds to enzyme and changes its shape

Loss of shape = loss of function

Access the text alternative for slide images.

Figure 5.8c Feedback Inhibition, concluded

c. Inactive enzyme and inactive pathway

Now the substrate can’t bind to enzyme and the reaction stops

When the product gets low, enzyme will go back to original shape.

Enzyme starts working again.

Energy of Activation

Energy of activation:

Molecules frequently do not react with each other unless activated.

Energy of activation (

)—energy needed to cause

molecules to react with one another

Enzymes lower the amount of energy required.

Enzymes bring substrates into contact and even sometimes participate in the reaction.

Figure 5.9 Energy of Activation (E sub a)

A LOWER hurdle is easier/faster to get over

A LOWER energy of activation makes a reaction easier/faster

Access the text alternative for slide images.

5.4 Cell Transport

Plasma membrane regulates traffic in and out of the cell.

Selectively permeable—some substances pass freely, some transported, some prohibited

Three ways to enter

Passive transport—substances move from higher to lower concentration, no additional energy is required.

Active transport—substances move from lower to higher concentration, additional energy is required.

Bulk transport—movement independent of gradients, additional energy is required.

Passive Transport

Passive transport:

No energy required for simple diffusion

Molecules move down their concentration gradient until equilibrium is reached.

Cell does not expend additional energy—molecules already in motion.

Some molecules slip between phospholipids.

Facilitated diffusion—others use transport protein specific to molecule

Water uses aquaporins—this explains faster than expected transport rate.

Figure 5.10 Simple Diffusion Demonstration

Access the text alternative for slide images.

Figure 5.11 Facilitated Diffusion

Access the text alternative for slide images.

Figure 5.12 Osmosis Demonstration

Access the text alternative for slide images.

Figure 5.13 Osmosis in Animal and Plant Cells—Isotonic Environment

Effect of osmosis on cells

Isotonic solution

No net gain or loss of water

Concentration of water same on both sides of the membrane

0.9% saline isotonic to red blood cells

Figure 5.13 Osmosis in Animal and Plant Cells—Hypotonic Environment

Hypotonic solution

Concentration of water outside cell greater than inside cell

Cell gains water.

Animal cells may lyse or burst

Plant cells use this to remain turgid.

Figure 5.13 Osmosis in Animal and Plant Cells—Hypertonic Environment

Hypertonic solution

Concentration of water outside cell less than inside cell

Cell loses water.

Animal cells shrink.

Plant cells undergo plasmolysis and may wilt.

Figure 5.14 Active Transport

Active transport:

Cells expend energy to move molecules against a concentration gradient.

Requires transport protein

Sodium–potassium pump is important in maintaining gradient of ions used in the nerve impulse conduction.

Access the text alternative for slide images.

Figure 5.15 Sodium–Potassium Pump

Access the text alternative for slide images.

Bulk Transport

Bulk transport:

Macromolecules are often too large to be moved by transport proteins.

Vesicle formation takes them in or out of cell.

Exocytosis—movement out of cell

Figure 5.16a Bulk Transport—Exocytosis

Access the text alternative for slide images.

Figure 5.15b Bulk transport—Endocytosis

Access the text alternative for slide images.

Endocytosis

Endocytosis—movement into cell

Phagocytosis—cell surrounds, engulfs, and digests particle

Pinocytosis—vesicle forms around liquid or small particles

Receptor-mediated endocytosis—receptors for particular substances found in coated pit—selective and more efficient.

Figure 5.17 Receptor-Mediated Endocytosis

Access the text alternative for slide images.

(photos): Mark Bretscher

End of Main Content

Because learning changes everything.®

www.mheducation.com

Accessibility Content: Text Alternatives for Images

Figure 5.1 Potential Energy Versus Kinetic Energy – Text Alternative

Return to parent-slide containing images.

Plants capture solar energy and store it as potential energy in different parts of the plant like fruits, stems, and leaves. When a man eats a fruit, the potential energy enters his body where it is transformed into kinetic energy when he moves from one location to another. At every stage of the energy flow, some energy is also lost as heat.

Return to parent-slide containing images.

Figure 5.2a Cells and Entropy – Text Alternative

Return to parent-slide containing images.

The photo on the left depicts a clean, organized room with everything in its right place. The right photo shows a dirty, disorganized room with items strew on the bed and the floor.

Return to parent-slide containing images.

Figure 5.3 ATP – Text Alternative

Return to parent-slide containing images.

The structure of ATP consists of adenine, ribose, and triphosphate bonded together.

Return to parent-slide containing images.

Figure 5.4 The ATP Cycle – Text Alternative

Return to parent-slide containing images.

The ADP combines with a P utilizing the energy from cellular respiration to give ATP. ATP releases energy for cellular activity (for example, protein synthesis, nerve conduction, muscle contraction) and breaks down into ADP and P. The structure of ADP consists of adenine, ribose, and diphosphate bonded together.

Return to parent-slide containing images.

Figure 5.5 Coupled Reaction – Text Alternative

Return to parent-slide containing images.

The reaction takes place as follows: Myosin assumes its resting shape when it combines with ATP. ATP splits into ADP and P, causing myosin to change its shape and allowing it to attach to actin. Release of ADP and causes myosin to again change shape and pull against actin, generating force and motion.

Return to parent-slide containing images.

Figure 5.6 Flow of Energy – Text Alternative

Return to parent-slide containing images.

Chloroplasts present in green plants trap solar energy and convert it into chemical energy (carbohydrate) through photosynthesis. Oxygen and heat are released during the process. Mitochondria convert chemical energy to ATP molecules, which are stored in cells. Cells use this stored energy in chemical work, transport work, and mechanical work. During cellular respiration in mitochondria, carbon dioxide and water are produced, which are utilized by chloroplast during photosynthesis.

Return to parent-slide containing images.

5.3 Metabolic Pathways and Enzymes – Text Alternative

Return to parent-slide containing images.

a. The first substrate S binds with the active site of enzyme E1 with another binding site also. Further, multiple enzymes E2, E3, and E4 also react in the metabolic pathway, and finally, end product P is formed.

b. The binding forms a product enzyme complex in which the shape of the active site is changed.

Return to parent-slide containing images.

Figure 5.8a Feedback Inhibition—Active Enzyme and Active Pathway – Text Alternative

Return to parent-slide containing images.

The first substrate S binds with the active site of enzyme E1 with another binding site also. Further, multiple enzymes E2, E3, and E4 also react in the metabolic pathway, and finally, end product P is formed.

Return to parent-slide containing images.

Figure 5.8b Feedback Inhibition – Text Alternative

Return to parent-slide containing images.

The binding forms a product enzyme complex in which the shape of the active site is changed.

Return to parent-slide containing images.

Figure 5.9 Energy of Activation (E sub a) – Text Alternative

Return to parent-slide containing images.

A curve labeled with enzyme starts from the reactants, reaches a small peak, and slopes down to the product. The energy of activation needed is less. A curve labeled without enzyme starts from the reactants, reaches a bigger peak, and slopes down to the product. The energy of activation needed is high.

Return to parent-slide containing images.

Figure 5.10 Simple Diffusion Demonstration – Text Alternative

Return to parent-slide containing images.

The diagram is discussed as follows:

a. A purple crystal of dye is placed in water at the bottom of the aquarium. Its molecular view shows separate groups of water and dye molecules.

b. After some time, the water of the aquarium starts turning purple. Due to the beginning of diffusion, the water and dye molecules are somewhat mixed in its molecular view.

c. After the passage of some more time, the water of the aquarium turns completely purple. The molecular view of the dye shows the equal distribution of water and dye molecules as a result of complete diffusion.

Return to parent-slide containing images.

Figure 5.11 Facilitated Diffusion – Text Alternative

Return to parent-slide containing images.

It shows a carrier protein embedded in the plasma membrane of a cell. The solute particles outside the cell enter the cell through the carrier protein.

Return to parent-slide containing images.

Figure 5.12 Osmosis Demonstration – Text Alternative

Return to parent-slide containing images.

The setup consists of a thistle tube with the broad end covered by a semipermeable membrane filled with 10% salt solution. It is immersed in a beaker containing 5% salt solution. After sometime, the concentration of the beaker solution becomes more than 5% and the solution in the thistle tube becomes less concentrated (less than 10%).

Return to parent-slide containing images.

Figure 5.14 Active Transport – Text Alternative

Return to parent-slide containing images.

From the left, the first diagram shows solute molecules outside of a cell moving toward the transport protein embedded in the bilayer of the plasma membrane. The adenosine triphosphate present inside the cell provides energy for the movement of the solutes. In the second diagram, the transport protein holds a solute by changing its shape accordingly. The breakdown of adenosine triphosphate molecules releases adenosine diphosphate and one phosphate group. The released phosphate group attaches to the transport protein towards the interior of the cell. The third diagram shows the release of the solute to the inside of the cell. The arrowheads show the direction of the movement of the solute. The phosphate group now dissociates from the transport protein, which again causes its shape to change.

Return to parent-slide containing images.

Figure 5.15 Sodium–Potassium Pump – Text Alternative

Return to parent-slide containing images.

The enlarged diagrams show a carrier protein with the phospholipid bilayer at the sides, along with the sodium and potassium cations. The six steps are as follows:

1. Carrier protein has a shape that allows it to take up three sodium cations.

2. Adenosine triphosphate (ATP) is split, and phosphate group attaches to carrier.

3. Change in shape results and causes carrier to release three sodium cations outside the cell.

4. Carrier has a shape that allows it to take up two Potassium cations.

5. Phosphate group is released from carrier.

6. Change in shape results and causes carrier to release two Potassium cations inside the cell.

Return to parent-slide containing images.

Figure 5.16a Bulk Transport—Exocytosis – Text Alternative

Return to parent-slide containing images.

A vesicle is formed inside the cell which fuses with the plasma membrane and ultimately discharges the vesicle content to the outside of the cell.

Return to parent-slide containing images.

Figure 5.15b Bulk transport—Endocytosis – Text Alternative

Return to parent-slide containing images.

It shows a vesicle-like pit formed inside the plasma membrane which ultimately forms a vesicle and moves inside the cell.

Return to parent-slide containing images.

Chapter 6

Energy for Life

Essentials of Biology

SEVENTH EDITION

Sylvia S. Mader Michael Windelspecht

Because learning changes everything.®

6.1 Overview of Photosynthesis

Photosynthesis

Transforms solar energy into chemical energy of carbohydrates

Plants, algae, and cyanobacteria

Producers—feed themselves and all of the consumers (most other living organisms on Earth)

Figure 6.1 Photosynthetic Organisms

(kelp): Chuck Davis/The Image Bank/Getty Images; (diatoms): ©Ed Reschke; (Euglena): M I (Spike) Walker/Alamy Stock Photo; (sunflower): Hammond HSN/Design Pics; (mosses): Steven P. Lynch; (cyanobacteria): John Hardy, University of Washington – Stevens Point Department of Biology

Figure 6.2 Leaves and Photosynthesis

Plants as photosynthesizers

Green portions carry on photosynthesis.

Carbon dioxide enters leaves through stomata.

Roots absorb water.

C O2 and H2O diffuse into mesophyll cells and then into chloroplasts.

Access the text alternative for slide images.

(mesophyll cell): Dr. David Furness, Keele University/Science Source; (chloroplast): Omikron/Science Source

Chloroplast

Chloroplast:

Double membrane surrounds stroma.

Third membrane forms thylakoids.

Grana—stacks

Thylakoid space

Chlorophyll and other pigments reside within thylakoid membrane.

Pigments absorb solar energy.

Carbon dioxide will be reduced in the stroma into carbohydrates.

Glucose is the chief organic energy source for most organisms.

The Photosynthetic Process 1

The photosynthetic process:

Begins with the end products of cellular respiration—C O2 and H2O

Hydrogen atoms removed from water are added to carbon dioxide.

Solar energy is required.

Oxygen is a by-product of the oxidation of water.

End product is CH2O or glucose C6H12O6.

Access the text alternative for slide images.

The Photosynthetic Process 2

Two sets of reactions

Light reactions

Occur in thylakoid membrane

Chlorophyll absorbs solar energy and energizes electrons.

Water is oxidized, releasing electrons, hydrogen ions, and oxygen.

ATP produced in electron transport chain

NADP⁺ → N A D P H

Calvin cycle reactions

Occur in stroma

C O2 taken up

ATP and N A D P H used to reduce C O2 to a carbohydrate.

Figure 6.4 The Photosynthetic Process

Access the text alternative for slide images.

6.2 The Light Reactions—Harvesting Energy

Pigments absorb solar energy.

Solar energy can be described in terms of its wavelength and energy content.

Visible light contains various wavelengths.

Shorter wavelengths contain more energy.

Longer wavelengths contain less energy.

Less than half of the solar radiation reaching the Earth hits the surface.

Vision and photosynthesis are adapted to use the most prevalent wavelengths (visible light).

Wavelengths and Pigments

Figure 6.5 The electromagnetic spectrum.

Figure 6.6 Photosynthetic pigments and photosynthesis.

Access the text alternative for slide images.

Photosynthetic Pigments

Photosynthetic pigments:

Most photosynthesizing cells have chlorophylls and carotenoids.

Both chlorophyll a and b absorb violet, blue, and red wavelengths better than other colors.

Because green is reflected, leaves appear green.

Accessory pigments, such as carotenoids, appear yellow or orange because they reflect those colors—they absorb light in the violet-blue-green range.

Accessory pigments become noticeable in fall when chlorophyll breaks down.

Figure 6.7 Leaf Colors 1

Chlorophylls absorb violet, blue, and red wavelengths best.

Leaves looks green because they reflect green light.

Chlorophylls cover up accessory pigments, which are more visible in autumn.

Access the text alternative for slide images.

(White Birch Forest): Exactostock/SuperStock

Figure 6.7 Leaf Colors 2

Carotenoids absorb violet, blue, green.

But reflect yellow-orange

Leaf looks yellow-orange.

When chlorophylls are no longer produced, we see the other pigments.

Access the text alternative for slide images.

(Silver Birch Forest): Ron Crabtree/Digital Vision/Getty Images

The Light Reactions: Capturing Solar Energy

Electron pathway of the light reactions

Capture sun’s energy and stores in the form of a hydrogen ion (H⁺) gradient

Gradient used to produce ATP

N A D P H is also produced

Figure 6.8 The Light Reactions of Photosynthesis

Access the text alternative for slide images.

The Light Reactions 1

Two photosystems used

Named for order discovered

Consist of pigment complex (contains chlorophyll and carotenoids) and an electron acceptor

Complex serves as antenna for gathering solar energy and passing it to the reaction center (chlorophyll a molecule).

The Light Reactions 2

Photosystem II

Absorption of solar energy energizes electrons.

Electrons escape to electron acceptor molecule.

Sent through electron transport chain

Replacement electrons obtained by splitting water

Releases oxygen gas as waste product

Electron transport chain

Series of carriers pass electrons along, releasing energy

Energy stored in the form of H⁺ gradient

Will be used to make ATP

Photosystem 1

Absorption of solar energy energizes electrons.

Electrons captured by another electron acceptor molecule.

Electrons and a hydrogen passed to NADP⁺ to become N A D P H.

Replacement electrons come from electron transport chain.

The Electron Transport Chain 1

Organization of thylakoid membrane

PS II, PS1, and the electron transport system are located within the thylakoid membrane.

Promotes efficient transfer of electrons

ATP synthase complex also here

ATP production

Thylakoid space is a reservoir for H⁺

Each time water is split, 2 H⁺ remain in thylakoid space.

Energy from electrons transferred between carriers used to pump more H⁺ from the stroma into the thylakoid space

Establishes H⁺ gradient = large amount of potential energy

The Electron Transport Chain 2

H⁺ gradient is used to produce ATP

The H⁺ flow down concentration gradient

Pass through ATP synthase complex

Energy release allows for production of ATP

Captures released energy

NADP⁺ is a coenzyme that accepts electrons and a H⁺ to become N A D P H.

Figure 6.9 The Electron Transport Chain 1

Access the text alternative for slide images.

Figure 6.9 The Electron Transport Chain 2

Access the text alternative for slide images.

6.3 The Calvin Cycle Reactions—Making Sugars

Occurs in stroma of chloroplasts

End product is glucose C6H12O6.

Three steps

Carbon dioxide fixation

Carbon dioxide reduction

Regeneration of first substrate (RuBP)

Fixation of Carbon Dioxide

Fixation of carbon dioxide:

C O2 from the atmosphere attached to RuBP by RuBP carboxylase (rubisco)

6-carbon molecule split into two 3-carbon molecules.

Reduction of Carbon Dioxide

Reduction of carbon dioxide:

Uses N A D P H (for electrons) and some ATP (for energy) from light reactions

Forms G3P, which can become glucose

Regeneration of RuBP

Regeneration of RuBP:

1 G3P can be made into glucose or other organic molecules.

5 G3P used to reform RuBP (5-carbon molecule)

Utilizes ATP from light reactions

Figure 6.10 The Calvin Cycle Reactions, C O2 Fixation

Access the text alternative for slide images.

Figure 6.10 The Calvin Cycle Reactions, C O2 Reduction

The Calvin cycle is divided into three portions: C O2 fixation, C O2 reduction, and regeneration of RuBP. Because five G3P are needed to re-form three RuBP, it takes three turns of the cycle to achieve a net gain of one G3P. Two G3P molecules are needed to form glucose.

Access the text alternative for slide images.

Figure 6.10 The Calvin Cycle Reactions, Regeneration of RuBP

Access the text alternative for slide images.

Figure 6.11 The Uses of G3P

Fate of G3P

Plants and algae can make any molecule they need from G3P.

Form amino acids, fatty acid, and glycerol

Form glucose for energy needs

Form sucrose for transport through plant

Form starch for storage

Form cellulose for cell walls

Access the text alternative for slide images.

6.4 Variations in Photosynthesis

Plants are adapted to the light and rainfall conditions of their environment.

C3 Photosynthesis

When light and rainfall are moderate:

Use C3 photosynthesis – C3 plant – C3 compound formed first after C O2 fixation

Figure 6.12 Carbon Dioxide Fixation in C3 Plants

Access the text alternative for slide images.

(photo): Nick Kurzenko/Alamy Stock Photo

Variations in Photosynthesis, C4 Photosynthesis

When weather is hot and dry, preventing water loss is critical.

Closing stomata to limit water loss also limits C O2 intake and allows O2 buildup.

Some types of plants use C4 photosynthesis – C4 plant – where a C4 compound formed first after C O2 fixation.

Comparing C3 and C4 Photosynthesis

C4 photosynthesis

Anatomy of C4 plant different from C3 plant

C3 plant has mesophyll cells arranged in parallel rows.

Calvin cycle and light reactions both occur here.

C4 plant has layered arrangement around leaf veins.

Chloroplasts in mesophyll cells fix C O2 only, shield bundle sheath cells from buildup of O2

Chloroplasts in bundle sheath cells carry out Calvin cycle only.

Partitioning of pathways in space

Figure 6.13 Comparison of C3 and C4 Plant Anatomy

Access the text alternative for slide images.

Comparing C3 and C4 Plants

C3 plants carry out both reactions in the mesophyll cell.

Advantage in moderate conditions

C4 plants partition reactions

Allows stomata to stay closed (conserving water) while avoiding oxygen exposure to rubisco

Advantage in hot, dry weather

Figure 6.14 Carbon Dioxide Fixation in C4 Plants

Access the text alternative for slide images.

(photo): Doug Wilson/USDA

C A M Photosynthesis

C A M photosynthesis:

Crassulacean-acid metabolism

Most succulents in a desert environment

Partitioning in time

During the night, C A M plants open stomata when it is cooler.

Use C3 molecules to fix C O2 forming C4 molecules

Store C4 molecules in vacuoles

During the day, keep stomata closed to avoid water loss

Release stored C O2 when N A D P H and ATP available from light reaction

Figure 6.15 Carbon Dioxide Fixation in a C A M Plant

Access the text alternative for slide images.

(photo): Dinodia/Pixtal/age fotostock

Evolutionary Trends

Evolutionary trends:

C4 plants most likely evolved in, and are adapted to, areas of high light, high temperature, and limited rainfall.

More sensitive to cold—C3 plants do better than C4 plants below 25°C

Over 20% of total annual plant growth is conducted by these plants despite only 4% of plant species being C4 plants.

Of the 18 most problematic weed plants on the planet, 14 are C4 plants.

C A M plants compete well with C3 or C4 when the environment is extremely arid.

C A M is quite widespread.

End of Main Content

Because learning changes everything.®

www.mheducation.com

Accessibility Content: Text Alternatives for Images

Figure 6.2 Leaves and Photosynthesis – Text Alternative

Return to parent-slide containing images.

The cross-section of a leaf part shows an upper cuticle, a chain of rectangular cells of the upper epidermis, layers of mesophyll cells consisting of chloroplasts, and a circular vascular bundle. The vascular bundle appears in the cut part of the leaf vein. A chain of rectangular cells of the lower epidermis is present at the lower side with a circular opening of stomata for absorbing carbon dioxide and releasing oxygen.

An enlarged view of a mesophyll cell shows several chloroplasts stacked inside a membrane.

An enlarged view of chloroplast shows the outer covering with a stack of disc-like structures labeled granum, and the fluid surrounding granum labeled stroma. Each disc-shaped component of the granum is labeled as thylakoid.

The micrograph of chloroplast shows dark green regions on roughly rectangular structures labeled granum and longitudinal and lateral blank spaces labeled stroma.

Return to parent-slide containing images.

The Photosynthetic Process 1 – Text Alternative

Return to parent-slide containing images.

a. Reaction shows that H two O plus C O two yields C H two O plus O two, or water reacts with carbon dioxide in presence of solar energy forming end products of carbohydrate and oxygen. Carbon dioxide undergoes reduction through the gain of electrons and forms carbohydrates. Water undergoes oxidation through the loss of electrons and forms oxygen.

Return to parent-slide containing images.

Figure 6.4 The Photosynthetic Process – Text Alternative

Return to parent-slide containing images.

The process takes place inside the chloroplast. The thylakoid membranes absorb the solar energy and water for the light reactions and produce oxygen. The ADP to ATP conversion and the NADP superscript positive to N A D P H conversion also take place inside the thylakoid. The Calvin’s cycle inside the chloroplast converts ATP to ADP and N A D P H to NADP superscript positive. It utilizes the C O2 and produces CH2O (carbohydrate).

Return to parent-slide containing images.

Wavelengths and Pigments – Text Alternative

Return to parent-slide containing images.

Figure 6.5: Wavelength and energy are represented with arrows, showing that as wavelength increases, energy decreases. The electromagnetic spectrum shows a continuum of 7 electromagnetic waves including gamma rays, X-rays, UV rays, infrared rays, micro-waves, and radio waves. The visible light spectrum, which lies between ultraviolet light and infrared light is expanded to show specific wavelengths marked as 380, 500, 600, and 750 nanometers each for different colors.

Figure 6.6: The horizontal axis represents wavelengths in nanometers ranging from 380 to 750. The vertical axis shows relative absorption ranging from low through high.

The line curve representing chlorophyll a has two distinct peaks, one in the range of violet to blue-violet light at around 400 nanometers and another in the range of red-orange light at around 700 nanometers. The line curve representing chlorophyll b has two peaks as well, one in the blue range at about 450 nanometers and one in the orange range at around 650 to 700 nanometers. The line curve of carotenoid has two distinct peaks in the blue-to-blue-green range, both between 400 and 500 nanometers.

Note: All data is approximate.

Return to parent-slide containing images.

Figure 6.7 Leaf Colors 1 – Text Alternative

Return to parent-slide containing images.

Green colored leaves are caused due to: Warm weather; more daylight hours, Much chlorophyll is produced, Leaf absorbs all colors of light but green. Hence we see reflected green light.

Return to parent-slide containing images.

Figure 6.7 Leaf Colors 2 – Text Alternative

Return to parent-slide containing images.

Yellow colored leaves are caused due to: Cool weather; fewer daylight hours, Little chlorophyll is produced, Leaf absorbs all colors but yellow to orange. We see reflected yellow to orange light.

Return to parent-slide containing images.

Figure 6.8 The Light Reactions of Photosynthesis – Text Alternative

Return to parent-slide containing images.

The photosynthesis process takes place inside the chloroplast. The thylakoid membranes absorb the solar energy and water for the light reactions and produce oxygen. The ADP to ATP conversion and the NADP superscript positive to N A D P H conversion also take place inside the thylakoid. The Calvin’s cycle inside the chloroplast converts ATP to ADP and N A D P H to NADP superscript positive. It utilizes the C O2 and produces CH2O (carbohydrate). The light reactions are as follows: water splits into two hydrogen molecules and half oxygen molecule while emitting an electron. It enters the pigment complex along with the solar energy. The electron from the pigment complex enters the electron acceptor, it enters the electron transport chain to PS1. ADP and P combine to form ATP. Electron from PS1 reaches electron acceptor and converts NADP positive and H positive to N A D P H. The ATP and N A D P H released enter the Calvin’s cycle.

Return to parent-slide containing images.

Figure 6.9 The Electron Transport Chain 1 – Text Alternative

Return to parent-slide containing images.

The photosynthetic reactions are as follows: In thylakoid space, the water splits into two hydrogen ions and half oxygen. The exited electron obtained from the splitting of water reaches photosystem two (PS 2) which is attached to the thylakoid membrane. Further, photosystem two traps solar energy and releases energized electron which is transferred to an electron transport chain The newly de-energized electrons from Photosystem two are taken up by Photosystem one (PS 1). Photosystem one also traps solar energy and releases an energized electron and passes it to NADP superscript positive, which then combines with H to form N A D P H. The hydrogen ion received from the splitting of water in thylakoid space and the electron transport chain transfers to the stroma through the protein complex ATP synthase. The ATP (adenosine triphosphate) formed from ADP (adenosine diphosphate) (ADP) and phosphate (P) and N A D P H are utilized by Calvin cycle reactions inside stroma.

Return to parent-slide containing images.

Figure 6.9 The Electron Transport Chain 2 – Text Alternative

Return to parent-slide containing images.

The photosynthetic reactions are as follows: In thylakoid space, the water splits into two hydrogen ions and half oxygen. The exited electron obtained from the splitting of water reaches photosystem two (PS II) which is attached to the thylakoid membrane. Further, photosystem two traps solar energy and releases energized electron which is transferred to an electron transport chain The newly de-energized electrons from Photosystem two are taken up by Photosystem one (PS I). A label reads, hydrogen is pumped from the stroma to the thylakoid space. Photosystem one also traps solar energy and releases an energized electron and passes it to NADP superscript positive, which then combines with H to form N A D P H. The hydrogen ion received from the splitting of water in thylakoid space and the electron transport chain transfers to the stroma through the protein complex ATP synthase. The other label reads, hydrogens flow back out into stroma through ATP synthase complex. The ATP (adenosine triphosphate) formed from ADP (adenosine diphosphate) (ADP) and phosphate (P) and N A D P H are utilized by Calvin cycle reactions inside stroma.

Return to parent-slide containing images.

Figure 6.10 The Calvin Cycle Reactions, C O2 Fixation – Text Alternative

Return to parent-slide containing images.

Key molecules of the Calvin Cycle are:

R u B P: ribulose-1,5-bisphosphate.

3PG: 3-phosphoglycerate.

BPG: 1,3-bisphosphoglycerate.

G3P: glyceraldehyde 3-phosphate.

Return to parent-slide containing images.

Figure 6.10 The Calvin Cycle Reactions, C O2 Reduction – Text Alternative

Return to parent-slide containing images.

At the end of the second stage, six molecules of glyceraldehyde-3-phosphate show the net gain of one glyceraldehyde-3-phosphate yielding glucose and other organic molecules.

Key molecules of the Calvin Cycle are:

R u B P: ribulose-1,5-bisphosphate.

3PG: 3-phosphoglycerate.

BPG: 1,3-bisphosphoglycerate.

G3P: glyceraldehyde 3-phosphate.

Return to parent-slide containing images.

Figure 6.10 The Calvin Cycle Reactions, Regeneration of RuBP – Text Alternative

Return to parent-slide containing images.

At left, in the chloroplast, solar energy is absorbed by the thylakoid membrane, where light reactions take place converting water into oxygen and producing N A D P H and ATP. These N A D P H and ATP are used by Calvin cycle reactions that occur inside the stroma. During the Calvin cycle, carbon dioxide gets converted into CH2O (carbohydrate). It also produces ADP with phosphate and NADP positive, which is again utilized in light reactions.

Three carbon dioxide molecules enter the Calvin cycle forming three hexose (glucose) molecules acting as intermediate. In carbon dioxide reduction, three hexose (glucose) molecules are transformed to six molecules of 3-phosphoglycerate which further gives six molecules of 1,3-bisphosphoglycerate. Here, six ATP received from light reaction converts to six ADP plus six phosphates. Further, six molecules of 1,3-bisphosphoglycerate on the conversion of six N A D P H into six NADP positive gives six molecules of glyceraldehyde-3-phosphate showing a net gain of one molecule of glyceraldehyde-3-phosphate, that yields glucose and other organic molecules. In the regeneration of ribulose-1,5-bisphosphate, three ATP received from light reactions convert into three ADP plus three phosphates, forming three molecules of ribulose-1,5-bisphosphate. Further, the carbon dioxide fixation occurs and the cycle continues.

Return to parent-slide containing images.

Figure 6.11 The Uses of G3P – Text Alternative

Return to parent-slide containing images.

G3P leads to amino acids, glycerol, fatty acids, and glucose phosphate. Glucose phosphate leads to starch, sucrose, and cellulose.

Return to parent-slide containing images.

Figure 6.12 Carbon Dioxide Fixation in C3 Plants – Text Alternative

Return to parent-slide containing images.

The Calvin cycle representation in the C3 plant, geranium shows the conversion of Carbon Dioxide into carbon three (C3) with the help of ribulose-1, 5-bisphosphate (RUBP) enzyme in the mesophyll cell, which further converts into glycerol 3-phosphate during the day.

Return to parent-slide containing images.

Figure 6.13 Comparison of C3 and C4 Plant Anatomy – Text Alternative

Return to parent-slide containing images.

The cross-section labeled C3 plant shows that the mesophyll cells are arranged in parallel layers containing vascular bundles with bundle sheath cells surrounding the vein. The bottom layer of the epidermis shows a stomatal opening between the epidermis cells.

The cross-section labeled C4 Plant shows that the mesophyll cells are arranged concentrically around the circular vascular bundles containing bundle sheath cells. The bottom layer of the epidermis shows a stomatal opening between the epidermis cells.

Return to parent-slide containing images.

Figure 6.14 Carbon Dioxide Fixation in C4 Plants – Text Alternative

Return to parent-slide containing images.

The Calvin cycle representation in C4 plant, corn shows the conversion of Carbon Dioxide into carbon four (C4) in the mesophyll cell, which converts into carbon dioxide in the bundle sheath cell, further converting into glycerol 3-phosphate during the day.

Return to parent-slide containing images.

Figure 6.15 Carbon Dioxide Fixation in a C A M Plant – Text Alternative

Return to parent-slide containing images.

The Calvin cycle representation in C A M plant pineapple shows the conversion of Carbon Dioxide into carbon four (C4) during the night, which converts into carbon dioxide, further converting into glycerol 3-phosphate during the day.

Return to parent-slide containing images.

image2.jpg

image3.jpg

image4.jpg

image5.jpg

image6.jpg

image7.jpg

image8.jpg

image9.png

image10.jpg

image11.png

image12.png

image13.jpg

image14.png

image15.png

image16.png

image17.png

image18.jpg

image19.jpg

image20.jpg

image21.jpg

image22.png

image1.png

Chapter 4

Inside the Cell

Essentials of Biology

SEVENTH EDITION

Sylvia S. Mader Michael Windelspecht

Because learning changes everything.®

4.1 Cells Under the Microscope

Cells

Are extremely diverse

Each type in our body is specialized for a particular function.

Nearly, all require a microscope to be seen.

Light microscope

Invented in the seventeenth century

Limited by properties of light

Electron microscope

Invented in 1930s

Overcomes limitation by using beam of electrons

Figure 4.1 Using Microscopes to See Cells

Access the text alternative for slide images.

(using TEM): The Center for Electron Microscopy and Analysis (CEMAS) at The Ohio State University/McGraw Hill; (epithelial cell): Dr. Kath White, photographer/EM Research Services, Newcastle University/McGraw Hill; (pluripotent stem cell): Steve Gschmeissner/Alamy Stock Photo; (using light microscope): Fuse/Corbis/Getty Images; (Euglena): Richard Gross/McGraw Hill

Figure 4.2 Relative Sizes of Some Living Things and Their Components

Access the text alternative for slide images.

The Limit to Cell Size

Why are cells so small?

Need surface areas large enough for entry and exit of materials

Surface-area-to-volume ratio

Small cells have more surface area for exchange.

Adaptations to increase surface area

Microvilli in the small intestine increase surface area for absorption of nutrients

Figure 4.3 Surface-Area-to-Volume Relationships

4.2 The Plasma Membrane

Marks boundary between outside and inside of a cell

Regulates passage in and out of a cell

Phospholipid bilayer with embedded proteins

Polar heads (hydrophilic) of phospholipids face into watery medium

Nonpolar tails (hydrophobic) face each other

Fluid mosaic model—the structure of the plasma membrane

Figure 4.4 A Model of the Plasma Membrane

Access the text alternative for slide images.

Figure 4.5a Membrane Protein Diversity—Channel Protein

Membrane proteins

Channel proteins

Form tunnel for specific molecules

Figure 4.5b Membrane Protein Diversity—Transport Protein

Transport proteins

Involved in passage of molecules through the membrane, sometimes requiring input of energy

Figure 4.5c Membrane Protein Diversity—Cell Recognition Protein

Cell recognition proteins

Enable our body to distinguish between our own cells and cells of other organisms

Figure 4.5d Membrane Protein Diversity—Receptor Protein

Receptor proteins

Allow signal molecules to bind, causing a cellular response

Figure 4.5e Membrane Protein Diversity—Enzymatic Proteins

Enzymatic proteins

Directly participate in metabolic reactions

Figure 4.5f Membrane Protein Diversity—Junction Proteins

Junction proteins

Form junctions between cells

Cell-to-cell adhesion and communication

4.3 The Two Main Types of Cells

Cell theory

All organisms are composed of cells.

All cells come only from preexisting cells.

All cells have:

A plasma membrane to regulate movement of material

Cytoplasm where chemical reactions occur

Genetic material for growth and reproduction

Two main types of cells

Based on organization of genetic material

Prokaryotic cells—lack membrane-bounded nucleus

Eukaryotic cells—have nucleus housing DNA

Prokaryotic Cells

Prokaryotic cells

Organisms from the domains Bacteria and Archaea

Generally smaller and simpler in structure than eukaryotic cells

Allows them to reproduce very quickly and effectively

Extremely successful group of organisms

Bacteria

Well known because some cause disease

Others have roles in the environment

Some are used to manufacture chemicals, food, drugs, and so on.

Bacterial Structure

Bacterial structure:

Cytoplasm surrounded by plasma membrane and cell wall

Sometimes a capsule—protective layer

Plasma membrane is the same as eukaryotes

Cell wall maintains the shape of a cell

DNA—single circular, coiled chromosome located in nucleoid (region—not membrane enclosed)

Ribosomes—site of protein synthesis

Appendages

Flagella—propulsion

Fimbriae—attachment to surfaces

Conjugation pili—DNA transfer

Figure 4.6 A Prokaryotic Cell

Access the text alternative for slide images.

(photo): Sercomi/Science Source

4.4 A Tour of the Eukaryotic Cell

Protists, fungi, plants, and animals

Have a membrane-bounded nucleus housing DNA

Much larger than prokaryotic cells

Compartmentalized and contain organelles

Four categories of organelles:

Nucleus and ribosomes

Endomembrane system

Energy-related

Cytoskeleton

Figure 4.7 Structure of a Typical Animal Cell

Access the text alternative for slide images.

(a): EM Research Services/Newcastle University

Figure 4.8a Structure of a Typical Plant Cell

Access the text alternative for slide images.

(a): Biophoto Associates/Science Source

Figure 4.8b Structure of a Typical Plant Cell

Access the text alternative for slide images.

Nucleus and Ribosomes

Nucleus and ribosomes:

Nucleus

Stores genetic information

Chromatin—diffuse DNA, protein, some RNA

Prior to cell division, DNA compacts into chromosomes

DNA organized into genes, which specify a polypeptide

Relayed to ribosome using messenger RNA (mRNA)

Nucleolus—region where ribosomal RNA (rRNA) is made

Nuclear envelope—double membrane

Nuclear pores permit passage in and out

Figure 4.9 Structure of the Nucleus

Access the text alternative for slide images.

(photo): Biophoto Associates/Science Source

Ribosomes

Carry out protein synthesis in the cytoplasm

Found in both prokaryotes and eukaryotes

Composed of two subunits

Mix of proteins and rRNA

Receive mRNA as instructions sequence of amino acids in a polypeptide

In eukaryotes:

Some ribosomes free in cytoplasm

Many attached to endoplasmic reticulum

Figure 4.10 The Nucleus, Ribosomes, and Endoplasmic Reticulum (ER)

Access the text alternative for slide images.

Endomembrane System 1

Endomembrane system:

Consists of nuclear envelope, membranes of endoplasmic reticulum, Golgi apparatus, and numerous vesicles

Helps compartmentalize cell

Restricts certain reactions to specific regions

Transport vesicles carry molecules from one part of the system to another.

Endoplasmic Reticulum

Endoplasmic reticulum:

Complicated system of membranous channels and saccules

Physically continuous with outer membrane of nuclear envelope

Rough ER

Studded with ribosomes

Modifies proteins in lumen

Forms transport vesicles going to Golgi apparatus

Smooth ER

Continuous with rough ER

No ribosomes

Synthesizes lipids like phospholipids and steroids

Function depends on cell

Produces testosterone, detoxifies drugs

Figure 4.11 Endoplasmic Reticulum (ER)

Access the text alternative for slide images.

(photo): Martin M. Rotker/Science Source

Figure 4.12 Endomembrane System

Access the text alternative for slide images.

Endomembrane System 2

Golgi apparatus

Stack of flattened saccules

Transfer station

Receives vesicles from ER

Modifies molecules within the vesicles

Sorts and repackages for new destination

Some are lysosomes.

Lysosomes

Vesicles that digest molecules or portions of the cell

Digestive enzymes

Tay-Sachs disease

Vacuoles

Vacuoles:

Membranous sacs

Larger than vesicles

Rid a cell of excess water

Digestion

Storage

Plant pigments

Animal adipocytes

Figure 4.13 Vacuoles

Access the text alternative for slide images.

(a): micro_photo/iStock/Getty Images; (b): Biophoto Associates/Science Source

Energy-Related Organelles

Energy-related organelles:

Mitochondria

Found in both plants and animals

Usually only visible under an electron microscope

Bounded by double membrane

Break down carbohydrates to produce adenosine triphosphate (ATP)

Cellular respiration—needs oxygen, produces carbon dioxide.

Inner membrane folds called cristae

Increase surface area

Inner membrane encloses matrix

Mixture of enzymes assisting in carbohydrate breakdown

Reactions permit ATP synthesis.

Matrix also contains its own DNA and ribosomes.

Chloroplasts

Chloroplasts:

Use solar energy to synthesize carbohydrates through the process of photosynthesis

Plants and algae

Three-membrane system

Double membrane enclosing stroma

Thylakoids formed from third membrane.

Thylakoid membrane contains pigments that capture solar energy

Chloroplasts have their own DNA and ribosomes.

Figure 4.14a Chloroplast Structure

Access the text alternative for slide images.

Figure 4.14b Electron Micrograph of a Chloroplast

(b): Omikron/Science Source

Figure 4.15 Mitochondrion Structure

Access the text alternative for slide images.

(b): Keith R. Porter/Science Source

The Cytoskeleton and Motor Proteins 1

The cytoskeleton and motor proteins:

Cytoskeleton—network of interconnected protein filaments and tubules

Extends from the nucleus to the plasma membrane

Only in eukaryotes

Maintains cell shape

Motor proteins—allow cell and organelles to move

Myosin, kinesin, and dynein

The Cytoskeleton and Motor Proteins 2

Motor proteins:

Instrumental in allowing cellular movements

Myosin

Interacts with actin

Cells move in amoeboid fashion

Muscle contraction

Kinesin and dynein

Move along microtubules

Transport vesicles from Golgi apparatus to final destination

Figure 4.16a Motor Proteins

Figure 4.16b Motor Proteins

The Cytoskeleton and Motor Proteins—Microtubules and Intermediate Filaments

Microtubules

Small, hollow cylinders

Assembly controlled by centrosome

Help maintain cell shape and act as track for organelles and other materials to move

Intermediate filaments

Intermediate in size

Ropelike assembly

Run from nuclear envelope to plasma membrane

Figure 4.17 Microtubules

Figure 4.18 Actin Filaments

Actin filaments:

Two chains of monomers twisted in a helix

Forms a dense web to support the cell

The Cytoskeleton and Motor Proteins—Centrioles

Centrioles:

Made of nine sets of microtubule triplets

Two centrioles lie at right angles

In animal cells; not present in plant cells

Figure 4.19 Centrioles

(photo): Don W. Fawcett/Science Source

Cilia and Flagella

Cilia and flagella:

Eukaryotes

For movement of the cell or fluids past the cell

Similar construction in both

9+2 pattern of microtubules

Cilia shorter and more numerous than flagella

Figure 4.20 Cilia and Flagella

Access the text alternative for slide images.

(a): (cilia): Cultura Creative Ltd/Alamy Stock Photo; (flagella of sperm): David M. Phillips/Science Source; (b): (flagellum cross section): Steve Gschmeissner/Science Source

4.5 Outside the Eukaryotic Cell

Plant cell walls

Primary cell walls

Cellulose fibrils and noncellulose substances

Wall stretches when cell is growing

Secondary cell walls (some plant cells)

Forms inside primary cell wall

Woody plants

Lignin adds strength

Plasmodesmata

Plant cells connected by numerous channels that pass through cell walls

For exchange of water and small solutes between cells

Figure 4.21 Animal Cell Extracellular Matrix

Access the text alternative for slide images.

Exterior Cell Surfaces in Animals

Exterior cell surfaces in animals:

No cell wall

Extracellular matrix (ECM)

Meshwork of fibrous proteins and polysaccharides

Collagen and elastin—well-known proteins

Matrix varies—flexible in cartilage, hard in bone

Cell Wall

Cell wall provides support to cell in many nonanimal cells

plant

fungi

protists

Extracellular Matrix

The extracellular matrix, found in animal cells, is a meshwork of fibrous proteins and polypeptides in close association with the cell that produced them.

Collagen—resists stretching

Elastin—provides resilience

Figure 4.22 Junctions Between Cells of the Intestinal Wall

Access the text alternative for slide images.

Adhesion Junctions

Junctions between cells

Adhesion junctions

Internal cytoplasmic plaques joined by intercellular filaments

Sturdy but flexible sheet of cells

Access the text alternative for slide images.

Tight Junctions

Junctions between cells

Tight junctions

Impermeable barrier

Adjacent plasma membraned joined

Access the text alternative for slide images.

Gap Junctions

Junctions between cells

Gap junctions

Allow communication between two cells

Adjacent plasma membrane channels joined

Access the text alternative for slide images.

End of Main Content

Because learning changes everything.®

www.mheducation.com

Accessibility Content: Text Alternatives for Images

Figure 4.1 Using Microscopes to See Cells – Text Alternative

Return to parent-slide containing images.

The first photo shows a scientist using an electron microscope. The second photo shows a transmission electron micrograph (TEM) of a cell showing its numerous organelles. The third photo shows a scanning electron micrograph (SEM) of a stem cell at 4,000 times magnification. The stem cell has two types of projections, small and circular, and numerous finger-like projections. The fourth photo shows a scientist using a light microscope. The fifth photo shows a light microscopic view of a Euglena at 470 times magnification. Euglena is an elongated cell with a red eyespot and many organelles.

Return to parent-slide containing images.

Figure 4.2 Relative Sizes of Some Living Things and Their Components – Text Alternative

Return to parent-slide containing images.

The scale shows the following: atoms: 0.1 nm, amino acids: 1 nm, proteins: 10 nm, viruses: 100 nm, chloroplast: 1 μm, most bacteria: 10 μm, plant and animal cells: 100 μm, human egg: more than 100 μm. Frog egg: 1 mm, ant: 1 cm, mouse: 0.1 m, man: 1 m, blue whale: 10 m. Organisms below 100 μm are categorized under electron microscope, organisms between 100 nm and 1 mm are under light microscope, organisms between 100 μm and 1 km are categorized under unaided eye.

Return to parent-slide containing images.

Figure 4.4 A Model of the Plasma Membrane – Text Alternative

Return to parent-slide containing images.

A magnified image of the plasma membrane of a cell shows a thick phospholipid bilayer. It consists of a polar head which is hydrophilic and nonpolar tails which are hydrophobic. Protein molecule, cholesterol, and glycol proteins are embedded in the bilayer. A carbohydrate chain is attached to the glycol protein. Cytoskeleton membranes emerge from the bottom. The upper surface is labeled external membrane surface and the lower surface is labeled internal membrane surface.

Return to parent-slide containing images.

Figure 4.6 A Prokaryotic Cell – Text Alternative

Return to parent-slide containing images.

The cylindrical cross-sectional diagram of a prokaryotic cell shows the labels and their descriptions as follows:

Capsule: Gel-like coating outside the cell wall.

Nucleoid: Location of the bacterial chromosome.

Ribosome: Site of protein synthesis.

Plasma membrane: Sheet that surrounds the cytoplasm and regulates entrance and exit of molecules.

Cell wall: Structure that provides support and shapes the cell.

Cytoplasm: Semifluid solution surrounded by the plasma membrane; contains nucleoid and ribosomes.

Flagellum: Rotating filament that propels the cell.

The micrograph of Escherichia coli shares the same top six labels of the diagram of the prokaryotic cell, other than the flagellum.

Return to parent-slide containing images.

Figure 4.7 Structure of a Typical Animal Cell – Text Alternative

Return to parent-slide containing images.

a. The micrograph shows five different cellular components including mitochondrion, nucleus, chromatin, peroxisome, and endoplasmic reticulum.

b. The cross-section of an animal cell shows 19 parts, labeled clockwise from bottom left as follows, Golgi apparatus, plasma membrane, cytoplasm, lysosome, smooth ER (Endoplasmic Reticulum), ribosome (attached to rough ER), mitochondrion, rough ER (Endoplasmic Reticulum), centrioles (in centrosome), vesicle, vesicle formation, nuclear envelope, nuclear pore, nucleolus, chromatin, filaments, microtubules, polyribosome (in cytoplasm), and ribosome (in cytoplasm). The nuclear envelope, nuclear pore, chromatin, and nucleolus are parts of the nucleus while filaments and microtubules are parts of the cytoskeleton.

Return to parent-slide containing images.

Figure 4.8a Structure of a Typical Plant Cell – Text Alternative

Return to parent-slide containing images.

It has the following parts labeled: chloroplast, cell wall, plasma membrane, nucleus, ribosomes, mitochondrion, peroxisome, and central vacuole.

Return to parent-slide containing images.

Figure 4.8b Structure of a Typical Plant Cell – Text Alternative

Return to parent-slide containing images.

It has the following parts labeled: cell wall, plasma membrane, cytoplasm, cell wall of adjacent cell, plasmodesmata, cytoskeleton: microtubule filaments, endomembrane system: rough ER, smooth ER, lysosome, Golgi apparatus, vesicle, energy organelles: chloroplast, mitochondrion, nucleus: ribosome (attached to rough ER), nuclear pore, chromatin, nucleolus, nuclear envelope, centrosome, central vacuole, ribosome in cytoplasm.

Return to parent-slide containing images.

Figure 4.9 Structure of the Nucleus – Text Alternative

Return to parent-slide containing images.

The cross-sectional diagram of an animal cell points to the enlarged view of the nucleus. The enlarged view of the nucleus shows eight labeled parts as follows: nuclear envelope consisting of outer membrane and inner membrane, nucleolus, chromatin, nucleoplasm, ER (Endoplasmic Reticulum) lumen, ribosome, endoplasmic reticulum, and nuclear pores.

The micrograph at 30,000 times magnification shows nuclear envelope containing numerous nuclear pores.

Return to parent-slide containing images.

Figure 4.10 The Nucleus, Ribosomes, and Endoplasmic Reticulum (ER) – Text Alternative

Return to parent-slide containing images.

The steps are as follows:

1) mRNA is produced in the nucleus but moves through a nuclear pore into the cytoplasm.

2) In the cytoplasm, the mRNA and ribosomal subunits join, and polypeptide synthesis begins.

3) If a ribosome attaches to a receptor on the ER, the polypeptide enters the lumen of the ER.

4) At termination, the polypeptide becomes a protein. The ribosomal subunits disengage, and the mRNA is released.

The labels include DNA, mRNA, and nuclear pore in the nucleus; cytoplasm; large unit; small subunit; polypeptide; ribosome; receptor; lumen of the ER; and ER membrane.

Return to parent-slide containing images.

Figure 4.11 Endoplasmic Reticulum (ER) – Text Alternative

Return to parent-slide containing images.

The cross-sectional diagram of the animal cell points to the enlarged view of the endoplasmic reticulum, which is attached to the nuclear envelope. Rough ER with ribosomes on its surface and smooth ER without ribosomes are also labeled. The micrograph shows the smooth ER and rough ER.

Return to parent-slide containing images.

Figure 4.12 Endomembrane System – Text Alternative

Return to parent-slide containing images.

Rough ER: synthesizes proteins and packages them in vesicles, transport vesicles contain products coming from ER. Golgi apparatus modifies lipids and proteins; sorts them and packages them in vesicles. Secretory vesicles fuse with the plasma membrane as secretion occurs. Smooth ER: synthesizes lipids and performs other functions. Transport vesicles contain products coming from ER. Lysosomes digest molecules or old cell parts. Incoming vesicles bring substances into the cell.

Return to parent-slide containing images.

Figure 4.13 Vacuoles – Text Alternative

Return to parent-slide containing images.

The micrograph of a plant cell labeled B, shows a roughly oval-shaped mitochondrion, nucleus, peroxisome adhered to the circumference, spots of ribosomes across the surface, an irregularly circular and large central vacuole, plasma membrane, external circumference of cell wall, and chloroplast.

Return to parent-slide containing images.

Figure 4.14a Chloroplast Structure – Text Alternative

Return to parent-slide containing images.

The cross-sectional diagram of a plant cell points to the enlarged diagram of the chloroplast labeled a. The enlarged diagram shows an oval-shaped structure covered with a double membrane: an outer membrane and an inner membrane. There are two distinct regions found inside the chloroplast called the granum and stroma. The space inside the inner membrane is filled with the homogenous matrix labeled stroma. A granum is made up of tight stacks of disc-shaped structures labeled thylakoids. The cut section of the thylakoid shows thylakoid space and thylakoid membrane.

Return to parent-slide containing images.

Figure 4.15 Mitochondrion Structure – Text Alternative

Return to parent-slide containing images.

The capsule shaped mitochondrion has the following parts labeled: outer membrane, inner membrane, matrix, and cristae.

Return to parent-slide containing images.

Figure 4.20 Cilia and Flagella – Text Alternative

Return to parent-slide containing images.

The micrographs and the diagram are as follows:

a. The micrograph shows hair-like cilia in the bronchial wall of lungs. Another micrograph of the sperm cell shows flagella of sperm attached to the oval heads.

b. The diagram shows a three-dimensional view of the structure of the flagella with five labels as follows: thin, tail-like flagellum, central microtubules, microtubule pairs, motor proteins, and plasma membrane of a cell. The TEM micrograph at 20,000 times magnification shows the cross-section of a flagellum with three joint labels, central microtubules, microtubule pairs, and motor proteins.

Return to parent-slide containing images.

Figure 4.21 Animal Cell Extracellular Matrix – Text Alternative

Return to parent-slide containing images.

It consists of an elastic fiber, collagen, polysaccharide, receptor protein, plasma membrane, cytoskeleton filament, and cytoplasm.

Return to parent-slide containing images.

Figure 4.22 Junctions Between Cells of the Intestinal Wall – Text Alternative

Return to parent-slide containing images.

A, Adhesion junction: The diagram shows the adhesion junction which forms a bridge between the plasma membranes of two adjacent cells. The parts labeled are intercellular space, filaments of cytoskeleton, plasma membranes, and intercellular filaments.

B, Tight junction: The diagram shows the tight junction which forms a protein that seals the plasma membranes of two adjacent cells. The parts labeled are intercellular space, tight junction proteins, and plasma membranes.

C, Gap junction: The diagram shows the gap junction which forms gap channels that link the plasma membranes of two adjacent cells. The parts labeled are plasma membranes, membrane channel, and intercellular space.

Return to parent-slide containing images.

Adhesion Junctions – Text Alternative

Return to parent-slide containing images.

Adhesion junction forms a bridge between the plasma membranes of two adjacent cells. The parts labeled are plasma membranes, filaments of cytoskeleton, intercellular filaments, and intercellular space.

Return to parent-slide containing images.

Tight Junctions – Text Alternative

Return to parent-slide containing images.

Tight junction forms proteins that seal the plasma membranes of two adjacent cells. The parts labeled are plasma membranes, tight junction proteins, and intercellular space.

Return to parent-slide containing images.

Gap Junctions – Text Alternative

Return to parent-slide containing images.

Gap junction forms gap channels that link the plasma membranes of two adjacent cells. The parts labeled are plasma membranes, membrane channel, and intercellular space.

image2.jpg

image3.png

image4.png

image5.png

image6.png

image7.png

image8.png

image9.png

image10.png

image11.png

image12.png

image13.png

image14.png

image15.png

image16.png

image17.png

image18.png

image19.png

image20.png

image21.png

image22.png

image23.png

image1.png

image2.jpg

image3.jpg

image4.jpg

image5.jpg

image6.jpg

image7.jpg

image8.jpg

image9.png

image10.jpg

image11.png

image12.png

image13.jpg

image14.png

image15.png

image16.png

image17.png

image18.jpg

image19.jpg

image20.jpg

image21.jpg

image22.png

image1.png

image2.jpg

image3.jpg

image4.jpg

image5.jpg

image6.jpg

image7.jpg

image8.jpg

image9.png

image10.jpeg

image11.jpg

image12.jpeg

image13.jpg

image14.jpg

image15.png

image16.jpg

image17.jpg

image18.png

image19.jpg

image20.jpg

image21.jpg

image22.jpg

image23.jpg

image24.jpg

image25.jpg

image26.png

image27.png

image28.png

image1.png

Order a similar assignment, and have writers from our team of experts write it for you, guaranteeing you an A

Order a similar assignment, and have writers from our team of experts write it for you, guaranteeing you an A