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Cellular Respiration
1. Define the two catabolic pathways:
a. Fermentation is a metabolic pathway that uses glucose to form ATP without
oxygen, the Kreb’s cycle, or the electron transport chain. It also forms another
end product besides ATP, either alcohol or lactic acid.
b. Cellular respiration is a metabolic pathway used in the production of ATP
where oxygen is used as a reactant. It uses the kreb’s cycle and the ETC.
2. Use the following terms correctly in a sentence: redox reactions, oxidation,
reduction, reducing agent and oxidizing agent.
A redox reaction is an electron transfer where one substance loses electons,
called oxidation, and is aided by the reducing agent, and another substance gains
elects, reduction, and is aided by the oxidizing agent.
3. Why is being “reduced” equivalent to having a greater potential energy?
Because in reduction, bonds are being formed due to the new electrons being
added. These bonds store energy, which is released when they are broken to form
new bonds. This energy changes from potential energy to actual energy.
4. In cellular respiration, what is being oxidized and what is being reduced?
Glucose is being oxidized and oxygen is being reduced.
5. Label the diagram below of the electron movement with regard to the coenzyme
NAD+.
6. Why are electron transport chains an advantage to living systems?
The ETC slowly releases energy stored in the electrons as they travel down each
gradient of the chain, so that an explosion doesn’t happen when the oxygen
combines with the electron. This makes the process stable so the living system
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doesn’t get injured by the increase in heat and light created by the energy.
7. What are the three stages of aerobic cellular respiration?
The three stages are glycolysis, Kreb’s cycle, and oxidative
phosphorylation/ETC/chemiosmosis.
8. What is substrate-level phosphorylation?
When ATP is formed by an enzyme transferring a phosphate to ADP.
9. Complete the chart below re: glycolysis
10. Label the transition reaction converting pyruvate to acetyl coA below:
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11. Label the citric acid cycle below:
a. Where does the C “go” that is removed?
It becomes CO2, which is then exhaled from the body.
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b. What is happening when NAD+  NADH + H+?
NAD+ is gaining an electron to be released in the ETC
c. Where is substrate level phosphorylation happening?
At step 5 where GTP is formed.
12. What is oxidative phosphorylation?
When ATP is produced using energy from the redox reactions of the ETC.
13. What are cytochromes?
Molecules that pass the electrons through the ETC
14.
Define chemiosmosis and label the diagram below.
chemiosmosis: a mechanism which uses the hydrogen ion gradient to move
energy through the inner mitochondria membrane, driving cellular work. Also
assists in the synthesis of ATP.
15. Label the diagram below of the activities occurring on the ECT.
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16. Complete the summary diagram of cellular respiration. You are responsible for
these #’s and locations!
17.
Label the diagram of fermentation below:
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18. Does aerobic cellular respiration happen in prokaryotic organisms – if yes –
where?
No because they don’t contain mitochondrion to complete the last two steps of
aerobic respiration.
19. What is the overall purpose of fermentation? Why does it have to occur?
Fermentation is an alternative way of making ATP. It has to occur in situations
where cells don’t have enough oxygen to use aerobic respiration.
20. What is a facultative anaerobe?
It is an organism that uses aerobic respiration to make ATP, but if oxygen is not
present it has the ability to swith to using fermentation to provide energy.
21. What is the evolutionary significance of glycolysis?
It is important because before cells developed enough to use oxygen for
respiration, they had to use glycolysis to make ATP.
22. Why do fats provide a little more than twice as many calories per gram as
compared to carbohydrates or proteins? Hint: Think of the output of the Citric Acid
Cycle.
When beta oxidation occurs, it breaks down fatty acids into 2-carbon molecules so
they can become Acetyl CoA. When this goes into the Kreb’s cycle, it yields twice
as many ATP
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23. Why would AMP stimulate cellular respiration and ATP inhibit it?
When ATP accumulates, it backs up the whole respiration system, so glycolysis
slows down. This makes the respiration speed up so it can get rid of the back up,
so ATP turns into ADP which goes to AMP.
24. Why would phosphofructokinase being allosteric in character be an advantage to
the control of cellular respiration?
Because phophofructokinase is allosteric, it has specific receptor sites for special
inhibitors and activators. This helps control respiration,.
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