Fermentation

Question 1

What is NAD+ derived from?

Answer 1

Niacin

Question 2

How is NAD+ regenerated after glycolysis?

Answer 2

From the metabolism of pyruvate

Question 3

Which reaction step in glycolysis is dependent upon NAD+ as an oxidizing agent?

Answer 3

The oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate.

Question 4

What are the final products formed from pyruvate in the presence of oxygen?

Answer 4

carbon dioxide and water (via TCA and electron transport chain)

Question 5

True or False: Fermentations are ATP-depleting processes in which organic compounds are both electron donors and acceptors.

Answer 5

False. Fermentations are ATP-generateing processes in which organic compounds are both electron donors and acceptors.

Question 6

By what process is NAD+ regenerated in muscle under anaerobic conditions?

Answer 6

Homolactic fermentation of pyruvate

Question 7

What enzyme catalyzes the oxidation of pyruvate and NADH to lactate and NAD+ in muscle under anaerobic conditions?

Answer 7

LDH (lactate dehydrogenase)

Question 8

True or false: The reaction from pyruvate tolactate is readily reversible.

Answer 8

True

Question 9

What causes the burn in legs when sprinting?

Answer 9

The 2 net H+ ions generated in conversion of 1 glucose to pyruvate to 2 lactate.

Question 10

What are the two possible fates for lactate?

Answer 10

1) Can be converted back to pyruvate

2) Can be carried to liver and used to synthesize glucose (this happens to most of it)

Question 11

What is the effect of high concentrations of lactate and H+ on hemoglobin?

Answer 11

Drops blood pH, pushes the Bohr curve to the right, pushing hemoglobin into the T conformation

Question 12

What is the net reaction for glycolysis through lactate formation?

Answer 12

glucose + 2 ADP + 2 Pi&raquo_space;» 2 lactate + 2 ATP + 2 H20 + 2 H+

Question 13

What two enzymes are required for alcohol fermentation in yeast?

Answer 13

1) Pyruvate decarboxylase

2) Alcohol dehydrogenase

Question 14

What are the products of alcoholic fermentation in yeast?

Answer 14

1) Pyruvate is converted to ethanol and CO2

2) NAD+ is regenerated for glycolysis

Question 15

How many reactions are required for alcoholic fermentation in yeast?

Answer 15

2

Question 16

Which enzyme required in alcoholic fermentation is not commonly (hardly ever) seen in humans?

Answer 16

pyruvate decarboxylase

Question 17

What coenzyme is always present with pyruvate decarboxylase?

Answer 17

thiamine pyrophosphate (TPP)

Question 18

What is thiamine pyrophosphate synthesized from? What is its functional group?

Answer 18

thiamine; thiazolium ring

Question 19

What types of reactions is thiamine pyrophosphate (TPP) mostly used in

Answer 19

alpha-keto acid decarboxylations

Question 20

What is thiamine deficiency called? What are the symptoms?

Answer 20

Beriberi; neurological disturbances, pain, paralysis, atrophy of limbs, edema, and/or death.

Question 21

What coenzyme should you suspect when you see a carboxylation reaction?

Answer 21

TPP (thiamine pyrophosphate)

Question 22

What enzyme catalyzes the reduction of acetaldehyde to ethanol?

Answer 22

ADH (alcohol dehydrogenase)

Question 23

What is required for the reduction of acetaldehyde to ethanol by ADH? What is regenerated?

Answer 23

NADH; NAD+