Bio102 Problems

Anaerobic Respiration

1.When proteins are used for energy, they usually enter the central metabolic pathways at which step?

A. Citric Acid Cycle

B. Transition Step

C. -Oxidation Cycle

D. Glycolysis

E. Electron Transport

2. The goal of fermentation is to

A. make ATP in the absence of oxygen.

B. produce oxidized co-enzymes.

C. produce lactate which can be used to synthesize amino acids.

D. move carbon-containing molecules into the mitochondria.

E. destroy co-enzymes that have been used up.

3. Which one of the following statements correctly describes feedback inhibition?

A. The substrate of a pathway is broken down by the pathway.

B. The substrate of a pathway is also a competitive inhibitor.

C. The end product of a pathway is also an allosteric inhibitor.

D. The end product of a pathway is removed from the cell.

E. The substrate of a pathway is also an allosteric inhibitor.

4.Is CO2 produced in anaerobic metabolism? If so, in which step of anaerobic metabolism?

5.What carbon-containing molecules are the substrates for -oxidation? What carbon-containing molecules are the products of -oxidation?

Substrate / Product
-oxidation

6.A very simplistic metabolic pathway is outlined below.

A / Enzyme #1
/ B / Enzyme #2
/ C / Enzyme #3
/ D / Enzyme #4
/ E

If we double the amount of molecule C present in the cell, how will that affect the rate at which enzyme #1 works? How will that affect the rate at which enzyme #4 works? Please explain your answer.

7.Name the cellular process that carries out the following energy transfers.

______transfers energy from a proton gradient to ATP.

______transfers energy from NADH and FADH2 to a proton gradient.

______transfers energy from NADH to lactate.

8.Name the cellular process that carries out the following carbon transformations.

______changes acetyl-CoA to CO2.

______changes one molecule of glucose into two molecules of pyruvate.

______changes pyruvate to ethanol and CO2.

______changes pyruvate to acetyl-CoA and CO2.

9. Why is a fermentation step required for a cell to survive anaerobically?

10. Which one statement is not true about AMPK (the AMP-dependent kinase)?

A. It phosphorylates many different proteins.

B. It’s activity leads to an increase in the amount of glycolytic enzymes.

C. It becomes active only when the cell is experiencing a shortage of ATP.

D. It is one of many substrates of PFK.

E. It increases the rate of glycolysis.

11. If a cell is deprived of oxygen, the Citric Acid Cycle always stops because

A. the cell dies.

B. pyruvate is no longer produced.

C. there are insufficient amounts of NAD+ and FAD available.

D. the G value for the synthesis of citrate becomes positive.

E. there is no way to produce any additional Ac-CoA, which is a substrate for the Citric Acid Cycle.

12. Phosphofructokinase (PFK) is a key enzyme in glycolysis and is heavily regulated. Which one mechanism listed below is NOT used to regulate PFK?

A. PFK can be allosterically activated by AMP.

B. PFK can be phosphorylated by AMPK.

C. More PFK can be produced by increasing transcription of the PFK gene.

D. PFK can be activated by having higher concentrations of its substrate.

E. PFK can be allosterically activated by ATP.

13. Which one type of molecule can be consumed anaerobically to produce ATP?

A. Complex carbohydrates

B. Fatty acids

C. Amino acids

D. Triglycerides

14. The product of one metabolic pathway is often the substrate for another metabolic pathway or process. For each pair of processes below, identify the product/substrate that connects the two.

Transition step /  /  / Citric acid cycle
Glycolysis /  /  / Transition step
-oxidation /  /  / Citric acid cycle

15. Why can your cells produce more usable cellular energy per carbon atom from a lipid molecule than from a carbohydrate molecule?

16. The AMPK enzyme becomes active when

A. PFK activity is inhibited.

B. AMP concentrations are high.

C. oxygen is abundant.

D. Photosystem II is inhibited.

E. ATP concentrations are high.

17. Glycolysis produces two molecules of ATP per molecule of glucose consumed. Despite this positive yield, a cell can’t survive by running only glycolysis. Why not?

18. Unlike carbohydrates, neither fats nor proteins can be burned for fuel anaerobically by humans. Why not?