General Biology 1004 Chapter 6 Lecture Handout, Summer ...dfrisby/downloads/ch6.pdf · General...

General Biology 1004 Chapter 6 Lecture Handout, Summer 2005Dr. Frisby

Slide 1

Copyright ©2004 Pearson Education , Inc. publishing as Benjamin Cummings

PowerPoint® Lecture Slides forEssential Biology, Second Edition & Essential Biology with Physiology

Neil Campbell, Jane Reece, and Eric Simon

Presentation prepared by Chris C. Romero

CHAPTER 6CHAPTER 6Cellular Respiration: Harvesting Chemical Energy

Slide 2

• When you exercise

BIOLOGY AND SOCIETY:FEELING THE “BURN”

– Muscles need energy in order to perform work– Your cells use oxygen to release energy from

the sugar glucose

Slide 3

• Aerobic metabolism

• Anaerobic metabolism


Slide 4• Physical conditioning

allows your body to adapt to increased activity

• Long-distance runners wait until the final sprint to exceed their aerobic capacity

Figure 6.1

Slide 5 ENERGY FLOW AND CHEMICAL CYCLING IN THE

BIOSPHERE• Fuel molecules in food represent solar

energy

• Animals depend on plants to convert solar energy to chemical energy

Slide 6

• Photosynthesis

Producers and Consumers


Slide 7• Autotrophs

• Heterotrophs

Slide 8• Producers

• Consumers

Figure 6.2

Slide 9

• The ingredients for photosynthesis are carbon dioxide and water

• Chloroplasts rearrange the atoms of these ingredients to produce sugars (glucose) and other organic molecules

Chemical Cycling BetweenPhotosynthesis and Cellular Respiration


Slide 10

Key Products of Photosynthesis

• Glucose• Oxygen

Slide 11• Both plants and animals perform cellular

respiration

• The waste products of cellular respiration, CO2 and H2O, are used in photosynthesis

Slide 12

Figure 6.3

Sunlightenergy

Ecosystem

Photosynthesis(in chloroplasts)

Glucose

Oxygen

Carbon dioxide

Cellular respiration(in mitochondria)

Water

for cellular work

Heat energy


Slide 13

• Cellular respiration

CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY

Slide 14

• Cellular respiration and breathing are closely related

The Relationship Between Cellular Respiration and Breathing

Slide 15

Figure 6.4

Breathing

Lungs

Musclecells

Cellularrespiration


Slide 16

• A common fuel molecule for cellular respiration is glucose

The Overall Equation for Cellular Respiration

Unnumbered Figure 6.1

Glucose Oxygen Carbondioxide

Water Energy

Slide 17

• During cellular respiration, hydrogen and its bonding electrons change partners

The Role of Oxygen in Cellular Respiration

Slide 18

• Chemical reactions that transfer electrons from one substance to another are called oxidation-reduction reactions

Redox Reactions


Slide 19

• The loss of electrons during a redoxreaction is called oxidation

• The acceptance of electrons during a redoxreaction is called reduction

Slide 20

Unnumbered Figure 6.2

[Oxygen gains electrons (and hydrogens)]

Oxidation[Glucose loses electrons (and hydrogens)]

Glucose Oxygen Carbondioxide

Water

Reduction

Slide 21• Why does electron

transfer to oxygen release energy?

Figure 6.5

Releaseof heatenergy


Slide 22• The path that

electrons take on their way down from glucose to oxygen involves many stops

NADH and Electron Transport Chains

Figure 6.6

1/2(from food via NADH)

2 H+ 2 e−Energy forsynthesis

of

Electron transport chain 2 e−

2 H+1 /2

Slide 23• The first stop is an electron acceptor

called NAD+

• The rest of the path consists of an electron transport chain

Slide 24

• Cellular respiration is an example of a metabolic pathway

• All of the reactions involved in cellular respiration can be grouped into three main stages

The Metabolic Pathway of Cellular Respiration


Slide 25 A Road Map for Cellular RespirationCytosol

Mitochondrion

High-energyelectronscarriedby NADH

High-energyelectrons carriedmainly byNADH

Glycolysis

Glucose2

Pyruvicacid

KrebsCycle Electron

Transport

Figure 6.7

Slide 26

Stage 1: Glycolysis• A molecule of glucose is split into two

molecules of pyruvic acid

Slide 27

• Glycolysis breaks a six-carbon glucose into two three-carbon molecules


Slide 28

Figure 6.8

Glucose

2 Pyruvic acid

Slide 29 • Glycolysis makes some ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP

Figure 6.9

Enzyme

Slide 30

Stage 2: The Krebs Cycle• The Krebs cycle completes the breakdown

of sugar


Slide 31 • In the Krebs cycle, pyruvic acid from glycolysis is first “prepped” into a usable form, Acetyl-CoA

Figure 6.10

CoA

1

2

3Pyruvic

acid

Aceticacid

Coenzyme A

Acetyl-CoA(acetyl-coenzyme A)

CO2

Slide 32

• The Krebs cycle extracts the energy of sugar by breaking the acetic acid molecules all the way down to CO2

Slide 33

Figure 6.11

Input

Acetic acid

ADP

3 NAD+

FAD

KrebsCycle

Output

2 CO21 2

3

4

5

6


Slide 34

Stage 3: Electron Transport• Electron transport releases the energy your

cells need to make the most of their ATP

Slide 35

• The molecules of electron transport chains are built into the inner membranes of mitochondria

Slide 36

• When the hydrogen ions flow back through the membrane, they release energy


Slide 37

Figure 6.12

Proteincomplex

Electroncarrier

Innermitochondrialmembrane

Electronflow

Electron transport chain ATP synthase

Slide 38The Versatility of Cellular

Respiration• Cellular respiration can “burn” other kinds of

molecules besides glucose

Slide 39

Figure 6.13

Food

Polysaccharides Fats Proteins

Sugars Glycerol Fatty acids Amino acids

Amino groups

Glycolysis Acetyl-CoA

KrebsCycle Electron

Transport


Slide 40 Adding Up the ATP from Cellular Respiration

Figure 6.14

Cytosol

Mitochondrion

Glycolysis

Glucose2

Pyruvicacid

2Acetyl-

CoA

KrebsCycle Electron

Transport

bydirectsynthesis

by directsynthesis

byATPsynthase

Maximumper

glucose:

Slide 41 FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY

• Some of your cells can actually work for short periods without oxygen

• Fermentation

Slide 42

• Human muscle cells can make ATP with and without oxygen

Fermentation in Human Muscle Cells


Slide 43

• Glycolysis is the metabolic pathway that provides ATP during fermentation

Slide 44

Figure 6.15a

2 ADP+ 2

Glycolysis

Glucose2 NAD+

2 Pyruvicacid + 2 H+

2 NAD+

2 Lacticacid

(a) Lactic acid fermentation

Slide 45

• Various types of microorganisms perform fermentation

Fermentation in Microorganisms


Slide 46

Figure 6.15b

2 ADP+ 2

2 ATPGlycolysis

Glucose2 NAD+

2 Pyruvicacid

2 CO2 released

+ 2 H+

2 NAD+

2 Ethylalcohol

(b) Alcoholic fermentation

Slide 47 • The food industry uses yeast to produce various food products

Figure 6.16

Slide 48

• Ancient bacteria probably used glycolysis to make ATP long before oxygen was present in Earth’s atmosphere

EVOLUTION CONNECTION:LIFE ON AN ANAEROBIC EARTH

– Glycolysis is a metabolic heirloom from the earliest cells that continues to function today in the harvest of food energy


Chapter 6 Study Objectives

1. Explain why we breathe faster when we exercise.2. Explain why an athlete switches from aerobic to anaerobic metabolism during strenuous

exercise.3. Explain why aerobic metabolism is better for an athlete than anaerobic metabolism.4. Describe where photosynthesis occurs, and explain why this process is important to

ecosystems.5. Define and compare autotrophs and heterotrophs, producers and consumers.6. Explain how the processes of photosynthesis and cellular respiration are complementary to

each other.7. Compare the processes of cellular respiration and breathing.8. Write and explain the overall equation for cellular respiration.9. Explain how the processes of oxidation and reduction are used to transfer electrons from

food molecules to NADH, the electron transport chain, and oxygen.10. Compare the reactants, products, and energy yield of the three stages of respiration

(glycolysis, Krebs cycle, and electron transport chain), then indicate where each processoccurs in the cell.

11. Compare the reactants, products, and energy yield of fermentation in human and yeastcells, then indicate where this process occurs in each type of cell.

12. Explain why it is likely that glycolysis is a primitive form of metabolism.

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