D2l Quizzes Ch. 10

Question 1

Although both pyruvate hehyrogenasecand glyceraldehyde 3- phosphate dehydrogenase use NAD+, the two enzymes do not compete for the same cellular NAD pool bc:

Answer 1

Pyruvate dehydrogenase is located in the mitochondrion, and glyceraldehyde 3-phosphate dehydrogenase in the cytosol

Question 2

What role do vitamins having a pyruvate dehydrogenase reaction? Choose the four correct answers.

Answer 2

1. Vitamin B five functions as an acid. Take care you’re using a high energy thioester bond formed in the E2 catalytic site
2. Vitamins provide functional chemical groups, and all three subunits of the PDH protein complex
3. Vitamin B three is a critical component of not only the PDH complex, but also the alpha ketoglutarate dehydrogenase complex, an enzyme in the citrate cycle
4. Riboflavin is an electron carrier that functions in a redox reaction involving dihydrolipoamide

Question 3

The pyruvate dehydrogenase reaction is regulated by

Answer 3

Allosteric control and covalent modification

Question 4

The disease beriberi is caused by nutritional deficiency in vitamin B one (thiamin). What key mitochondrial enzyme uses thiamin as a coenzyme in a reaction that generates acetyl-CoA, CO2, and NADH + H+ as products; and why is this condition rare in developed countries?

Answer 4

Pyruvate dehydrogenase; beriberi is rare because many common foods or vitamin-fortified

Question 5

How would a high NADH to NAD+ ratio be expected to affect the pyruvate dehydrogenase reaction?

Answer 5

Pyruvate, dehydrogenase kinase activity would increase, resulting in an increase in pyruvate dehydrogenase activity

Question 6

What is the bio chemical explanation for the observed toxic affects of arsenic contaminated well water in Bangladesh? Choose 2 best answers

Answer 6

1. Arsenic is converted to arsenite, which covalently modifies reduce lipoamide, there by inhibiting activity of the pyruvate dehydrogenase complex and blocking conversion of pyruvate to acetyl-CoA.
2. They are scenic contaminated, well water caused inhibition of dehydrolipoyl transacetylase, which is an enzyme, subunit required for metabolism of rice starch, the source of 70% of their daily calorie intake

Question 7

What are two reasons why human vitamin deficiencies are very rare developed countries?

Answer 7

Some processed foods contain add vitamins, in a variety of vegetables are readily available

Question 8

Choose the one best answer, explaining how oxaloacetate and acetyl-CoA levels are balance to maximize flux through the citrate cycle when energy charge in the cell is low

Answer 8

Pyruvate dehydrogenase is activated by CoA but inhibited by its product acetyl-CoA, whereas pyruvate carboxylase is activated by acetyl-CoA to produce more oxaloacetate for the citrate synthase reaction

Question 9

The eight reactions of the___ cycle oxidize__ to generate__ CO2, reduce three___ and___ FAD, and generate on 1__

Answer 9

Citrate, acetyl-CoA, 2,NAD+, 1,GTP

Question 10

Match the citrate cycle enzyme with the type of bio chemical reaction it catalyzes:
1. Dehydrogenation reaction.
2. Dehydration reaction.
3. Condensation reaction.
4. Substrate level phosphorylation reaction.
5. Oxidative decarboxylation reaction.

Answer 10

1. Citrate synthase
2. Succinylcholine-CoA synthase
3. Malate dehydrogenase.
4. Aconitase
5. Isocitrate dehydrogenase

Question 11

What are the following steps in a pyruvate dehydrogenase reaction:
- The acetyl group is transferred to CoA, forming acetyl CoA
- Electrons from FADH2 are transferred to NAD+ forming NADH and H+
-pyruvate and thiamine pyrophosphate react to form hydroxyethyl-TPP. CO2 is released
-The reduced coenzyme bound to PDH Israel oxidized using electrons from FAD
-An acetyl group is added to a coenzyme bound to PDH, forming acetyl-dihydrolipoamide

Answer 11

3,5,1,4,2

Question 12

The purpose of the first three steps in the pyruvate dehydrogenase reaction is to

Answer 12

Form acetyl-CoA