Ch 13.1 Glycolysis

Question 1

What is the role of ATP in coupled processes?

Answer 1

ATP is often involved in coupled processes.

Question 2

What does ATP hydrolysis provide energy for?

Answer 2

ATP hydrolysis provides the energy for glucose phosphorylation.

Question 3

Why does ATP hydrolysis release so much energy?

Answer 3

The ATP hydrolysis products are more stable than the reactants, making its hydrolysis reaction highly exergonic (ΔG ≪ 0).

Question 4

What is one reason thioester hydrolysis releases a large amount of free energy?

Answer 4

Thioester hydrolysis is more exergonic than the hydrolysis of an ordinary (oxygen) ester.

Question 5

What is activation in metabolic pathways?

Answer 5

Activation is the formation of a more reactive, higher energy substance that causes the next reaction to be exergonic.

Question 6

What is coenzyme A (CoA-SH)?

Answer 6

Coenzyme A is a key co-enzyme in biochemical pathways.

Question 7

What happens to molecules added to the sulfhydryl end of Coenzyme A?

Answer 7

Molecules can be added as a priming step for their subsequent release in an exergonic step.

Question 8

What vitamin is ascorbic acid and what is its biochemical function?

Answer 8

Ascorbic acid (C) is a cofactor for hydroxylation of collagen.

Question 9

What is the human deficiency disease associated with ascorbic acid?

Answer 9

Scurvy.

Question 10

What is the function of biotin (B7) in metabolism?

Answer 10

Biotin is a cofactor for carboxylation reactions.

Question 11

What is the human deficiency disease associated with cobalamin (B12)?

Answer 11

Anemia.

Question 12

What does folic acid function as in biochemical reactions?

Answer 12

Folic acid is a cofactor for one-carbon transfer reactions.

Question 13

What is the human deficiency disease associated with folic acid?

Answer 13

Anemia.

Question 14

What is lipoic acid’s role in metabolism?

Answer 14

Lipoic acid serves as a cofactor for acyl transfer reactions.

Question 15

What does nicotinamide (B3) do in biochemical pathways?

Answer 15

Nicotinamide is a cofactor for oxidation-reduction reactions.

Question 16

What is the human deficiency disease associated with niacin (B3)?

Answer 16

Pellagra.

Question 17

What is the role of pantothenic acid (B5) in metabolism?

Answer 17

Pantothenic acid is a cofactor for acyl transfer reactions.

Question 18

What is the function of pyridoxine (B6) in biochemical reactions?

Answer 18

Pyridoxine is a cofactor for amino-group transfer reactions.

Question 19

What is the role of riboflavin (B2) in metabolism?

Answer 19

Riboflavin acts as a cofactor for oxidation-reduction reactions.

Question 20

What is thiamine (B1) required for in metabolism?

Answer 20

Thiamine is a cofactor for aldehyde transfer reactions.

Question 21

What is the human deficiency disease related to thiamine?

Answer 21

Beriberi.

Question 22

How can cells regulate flux through a metabolic pathway?

Answer 22

By adjusting the rate of a reaction with a large free energy change.

Question 23

What are the goals of glycolysis?

Answer 23

• Formation of high-energy molecules (ATP and NADH) as cellular energy sources
• Production of pyruvate for additional ATP and NADH from the citric acid cycle
• Production of six- and three-carbon intermediate compounds for other cellular purposes.

Question 24

What is the first phase of glycolysis known as?

Answer 24

The investment phase.

Question 25

What type of reaction occurs in the first five steps of glycolysis?

Answer 25

Investment phase reactions.

Question 26

What mnemonic can help remember the steps of glycolysis?

Answer 26

Goodness Gracious Father Franklin Did Go By Picking 2 Pumpkins to Prepare Pie.

Question 27

What is the first enzyme involved in glycolysis?

Answer 27

Hexokinase.

Question 28

What type of reaction does phosphoglucose isomerase catalyze?

Answer 28

Isomerization.

Question 29

What is the key regulatory enzyme in glycolysis?

Answer 29

Phosphofructokinase.

Question 30

What does fructose-2,6-bisphosphate do in glycolysis?

Answer 30

It is the most potent activator of phosphofructokinase in mammals.

Question 31

What is the reaction catalyzed by aldolase in glycolysis?

Answer 31

Fructose-1,6-bisphosphate is split into two 3-carbon fragments.

Question 32

What type of reaction does triose phosphate isomerase catalyze?

Answer 32

Isomerization.

Question 33

What is the result of the GAP dehydrogenase reaction?

Answer 33

Oxidation of glyceraldehyde-3-phosphate, reducing NAD+ to NADH.

Question 34

What is substrate-level phosphorylation?

Answer 34

The transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP.

Question 35

What type of reaction is catalyzed by enolase?

Answer 35

Dehydration of 2-phosphoglycerate to form phosphenolpyruvate (PEP).

Question 36

What happens during the pyruvate kinase reaction?

Answer 36

Conversion of PEP to pyruvate with the production of ATP.

Question 37

What is the net equation for glycolysis?

Answer 37

C6H12O6 + 2 NAD+ + 2 HPO4^2- + 2 ADP → 2 C3H4O3 + 2 NADH + 2 ATP + 2 H2O + 2 H+.

Question 38

What three reactions exhibit particularly large decreases in free energy during glycolysis?

Answer 38

The specific reactions are not detailed in the text.

Question 39

What are the main products of glycolysis?

Answer 39

2 Pyruvate, 2 NADH, 2 ATP, 2 H2O, 2 H+ ## Footnote Glycolysis converts glucose into pyruvate while producing NADH and ATP.

Question 40

Which reactions in glycolysis exhibit large decreases in free energy?

Answer 40

Hexokinase (HK), Phosphofructokinase (PFK), Pyruvate kinase (PK) ## Footnote These reactions are exergonic and are key control points in glycolysis.

Question 41

What is the role of hexokinase in glycolysis?

Answer 41

Catalyzes the first step of glycolysis ## Footnote Hexokinase initiates the conversion of glucose to glucose-6-phosphate.

Question 42

What is the role of phosphofructokinase in glycolysis?

Answer 42

Catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate ## Footnote PFK is a key regulatory enzyme in glycolysis.

Question 43

What is the role of pyruvate kinase in glycolysis?

Answer 43

Catalyzes the conversion of phosphoenolpyruvate to pyruvate ## Footnote PK is another crucial regulatory point in glycolysis.

Question 44

How is pyruvate kinase activated?

Answer 44

Activated by fructose-1,6-bisphosphate (F1,6BP) ## Footnote This is an example of feedforward activation.

Question 45

What inhibits pyruvate kinase?

Answer 45

ATP ## Footnote High levels of ATP signal sufficient energy, inhibiting PK.

Question 46

What happens to pyruvate in aerobic organisms?

Answer 46

Converted to acetyl CoA for entry into the citric acid cycle ## Footnote Pyruvate is a key metabolite linking glycolysis and the citric acid cycle.

Question 47

What is a fate of pyruvate during intense exercise?

Answer 47

Converted to lactate ## Footnote This process helps regenerate NAD+ and is sometimes referred to as the eleventh step of glycolysis.

Question 48

What is the significance of lactate conversion?

Answer 48

Regenerates NAD+ ## Footnote This is crucial for maintaining glycolysis under anaerobic conditions.

Question 49

Who coined the term fermentation?

Answer 49

Louis Pasteur ## Footnote He described fermentation as life processes occurring without air.

Question 50

What is the precursor of oxaloacetate?

Answer 50

Pyruvate ## Footnote Oxaloacetate is important for gluconeogenesis and amino acid synthesis.

Question 51

Fill in the blank: The three main enzymes that control glycolysis are hexokinase, phosphofructokinase, and _______.

Answer 51

pyruvate kinase

Question 52

True or False: Pyruvate can be further oxidized to produce acetyl CoA.

Answer 52

True

Question 53

What type of control do the enzymes in glycolysis exhibit?

Answer 53

Allosteric control ## Footnote This allows for regulation based on the cell's energy needs.

Question 54

What is the mechanism of pyruvate carboxylase?

Answer 54

Utilizes a vitamin to transfer a COO- group ## Footnote This enzyme is involved in converting pyruvate to oxaloacetate.

Question 55

what are the energetic cliffs in glycolysis?

Answer 55

hexokinase, phosphofructokinase, and pyruvate kinase

Question 56

why are hexokinase, phosphofructokinase, and pyruvate kinase candidates for metabolic regulation?

Answer 56

because they are far from equilibrium, they are committed steps with very favorable change in energy