Bio 101
Intro to Cell and Molecular Biology
Lake Tahoe Community College
Instructor: Sue Kloss
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Chapter 6 - Cellular Respiration
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I. Cell respiration banks energy in ATP molecules.
A. C6H12O6 – glucose
B. Producers and consumers
1. photosynthesis
2. autotrophs
3. heterotrophs
4. producers
5. consumers
II. Basic mechanisms of energy release and storage
A. cells tap energy from electrons
1. energy contained in the specific arrangement of electrons
2. cell energy
3. cell respiration dismantles glucose
4. electrons are shuttled from molecules of hi energy to ones of low energy.
5. the reactions release energy in small amounts
6. cell transfers energy from glucose to ATP
B. Hydrogen carriers like NAD+ shuttle electrons in redox reactions
1. oxidation-reduction, or redox
2. transfer requires donor and acceptor.
3. example of redox reaction
4. NADH is now an energy carrier
C. respiration of breathing vs. cellular respiration
D. Redox reactions release energy
1. Glucose is like an “electron bank”
2. NAD+ and dehydrogenase
3. electron carrier molecule
4. NAD+ is recycled in the cell
5. electron carrier gains electrons
6. each carrier is a different molecule
7. Each downhill carrier has a greater affinity for electrons than uphill neighbor
E. 2 mechanisms generate ATP
1. cells generate ATP by phosphorylation
2. 2 ways to do phosphorylation
3. chemiosmosis
4. substrate level phosphorylation
III. Stages of cell respiration and fermentation
A. Respiration occurs in 3 main stages
1. glycolysis and Krebs cycle are exergonic
2. 3rd stage of respiration is electron transport chain (etc) B. Glycolysis harvests chemical energy by oxidizing glucose into pyruvic acid
1. Glycolysis
C. Pyruvic Acid is groomed for Krebs cycle
1. pyruvic acid diffuses from cytoplasm into mitochondria, where Krebs cycle occurs
2. it must be altered
D. Krebs cycle completes oxidation of organic fuels, generates many molecules of NADH and FADH2
1. Coenzyme A
E. Chemiosmosis powers most ATP production
1. final stage of cell respiration is electron transport chain and chemiosmosis
2. mitochondria can use the energy stored in the H+ concentration to drive the reaction (making ATP)
3. Electron transport chain of cell respiration is built into the inner membrane.
4. Most carrier molecules are in protein complexes which span the inner membrane
5. a concentration gradient of H+ ions develops between the inner and outer membranes.
6. ATP synthase is the port
7. cell couples the exergonic process of chemiosmosis with the endergonic production of ATP
F. Review: Each molecule of glucose yields many molecules of ATP
G. Fermentation is an anaerobic alternative to aerobic respiration
1. yeasts typically perform aerobic respiration
2. they can also survive anaerobically
3. convert pyruvic acid to CO2 and ethanol - alcoholic fermentation
4. Lactic acid fermentation
Due meeting 1 week 5
Ch. 6 Lesson Objectives
1. Describe the point at which athletes switch from aerobic to anaerobic metabolism during exercise.
2. Draw a model to demonstrate where photosynthesis occurs and how it is complementary to cellular respiration. Distinguish
between cellular respiration and breathing.
3. describe the overall chemical equation for cell respiration. Explain how the human body uses its daily supply of ATP.
4. Describe in general terms that you could use to explain to your friend (who is not taking biology), what are the 3 main
stages of aerobic cellular respiration, and what conceptually occurs in each stage to show how energy in a glucose molecule is
made available to the cell in cellular respiration
5. Define oxidation and reduction and relate these processes to chemical energy losses and gains
6. explain how redox reactions are used in cell respiration. List the molecules involved and describe the process briefly!
7. Draw and label, and write a brief paragraph to describe the role of electron transport chain and chemiosmosis in cell
respiration.
8. Compare the process of substrate level phosphorylation with chemiosmosis.
Due meeting 2 week 5
9. Draw a model of cellular respiration. Show where the reactants enter the process, and where products and energy are
yielded in the 3 stages of respiration. Also indicate where each process occurs in a cell.
10. Draw a diagram to depict fermentation, showing location in a cell, reactants, products and energy yield.
11. Compare the reactants, products and energy yield of alcoholic and lactic acid fermentation.