Module 12

Question 1

What are the net products of glycolysis from one glucose?

Answer 1

2 NADH, 2 ATP, 2 pyruvate

Question 2

How does glucose enter the cell?

Answer 2

GLUT transporters

Question 3

Where does glycolysis occur at?

Answer 3

in the cytosol

Question 4

What is the reactants and products in the first step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 4

Glucose + ATP to Glucose-6-phosphate + ADP + H+
Hexokinase, Mg++

Question 5

What does Mg+ do as a cofactor in kinase reactions?

Answer 5

shields negative charge to make the phosphoanhydride bond more attackable

Question 6

What are the steps in glycolysis that are irreversible, and what are their delta Gs?

Answer 6

the first, third and last step
very negative delta G

Question 7

What do kinase enzymes do?

Answer 7

transfer phosphate groups from ATP to another metabolite.

Question 8

What is the reactants and products in the second step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 8

G6P to Fructose-6-phosphate
phosphoglucose isomerase

Question 9

What is the point of the second step of the reaction?

Answer 9

prepares for an aldol cleavage step later on

Question 10

What type of reaction is the second step of glycolysis?

Answer 10

Acid/Base reaction

Question 11

What is the reactants and products in the third step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 11

F6P + ATP to Fructose-1,6-biphosphate + ADP + H+
phosphofructokinase, Mg++

Question 12

Which carbon is phosphorylated in the third step of glycolysis?

Answer 12

C1

Question 13

What is the reactants and products in the fourth step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 13

FBP to dihydroxyacetone phosphate and Glyceraldehyde-3-phosphate

aldolase

Question 14

What are two important residues for the fourth step of glycolysis?

Answer 14

base (deprotonated tyrosine/aspartate)
electron withdrawing group (lysine)

Question 15

What is the reactants and products in the fifth step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 15

DHAP to GAP
(ketose) (aldose)
Triose phosphate isomerase

Question 16

What is the reactants and products in the sixth step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 16

GAP and NAD+ to 1,3-bisphosphoglycerate + NADH + H+
glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and NAD+

Question 17

What is being oxidized in the sixth step of glycolysis?

Answer 17

a aldehyde is being oxidized to glycerate

Question 18

Why is the 1,3-bisphosphoglycerate product in the sixth step considered high energy?

Answer 18

The C1-acyl phosphate bond have a high hydrolysis exergonic reaction

Question 19

What is a mechanism layout of the sixth step of glycolysis?

Answer 19

GAPDH catalyzes the oxidation of GAP , where a cysteine residue forms a thioester intermediate that is then attacked by inorganic phosphate to produce 1,3 BPG.
During this process, NAD⁺ is reduced to NADH, capturing the energy from the oxidation.

Question 20

How many BPG is produced in the sixth step of glycolysis per glucose?

Answer 20

2 per glucose

Question 21

What is the reactants and products in the seventh step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 21

1,3 BPG and ADP to 3-phosphoglycerate + ATP
Phosphoglycerate kinase, Mg++

Question 22

What type of phosphorylation is occurring in the seventh step of glycolysis?

Answer 22

substrate-level phosphorylation, transferring a phosphate from C1 of 1,3 BPG to ADP

Question 23

What is the reactants and products in the eighth step in glycolysis?
What is the enzyme and cofactor attached to this reaction?

Answer 23

3-phosphoglycerate to 2-phosphoglycerate

phosphoglycerate mutase

Question 24

What do mutases do?

Answer 24

transfer a functional group from one position to another in a molecule

Question 25

What do mutases have in their active site?

Answer 25

a copy of the functional group of interest

Question 26

What is the reactants and products in the ninth step in glycolysis? What is the enzyme and cofactor attached to this reaction?

Answer 26

2-phosphoglycerate to phosphoenolpyruvate + H2O enolase

Question 27

Why is PEP a higher energy configuration than 2PG in glycolysis?

Answer 27

in PEP, the double bond next to the alcohol makes it likely for a tautomerization into the ketone, making PEP unstable in the end form.

Question 28

What is the reactants and products in the last step in glycolysis? What is the enzyme and cofactor attached to this reaction?

Answer 28

Phosphoenolpyruvate + ADP + H+ to pyruvate and ATP pyruvate kinase, Mg++

Question 29

What contributes to the negative delta G of the last reaction?

Answer 29

hydrolysis and tautomerization

Question 30

What is hexokinase regulated by?

Answer 30

product inhibition from glucose-6-phosphate

Question 31

Why is hexokinase not a primary point of control?

Answer 31

glycogen can be broken down to make G-6-P, therefore skipping step 1 entirely

Question 32

Why is pyruvate kinase not a primary point of control?

Answer 32

last step of pathway

Question 33

What is pyruvate kinase regulated by?

Answer 33

feedforward activation by FBP and PEP, feedback inhibition by ATP

Question 34

What are allosteric activators for phosphofructokinase and what do they stabilize?

Answer 34

AMP, ADP, Fructose 2,6-bisphosphate stabilize the R state which increase affinity for F6P

Question 35

What are allosteric inhibitors for phosphofructokinase and what do they stabilize?

Answer 35

ATP, PEP, citrate stabilize the T state which has decreased affinity for the substrate F6P

Question 36

How does allosteric activators work in PFK?

Answer 36

conformational shift positioning Arg next to a partially negative part of F6P

Question 37

How does allosteric inhibitors work in PFK?

Answer 37

glutamate is position next to F6P, leading to electrostatic repulsion and the T state

Question 38

What is the point of fermentation?

Answer 38

regenerate NAD+ for glycolysis

Question 39

What form of fermentation occurs in mammals?

Answer 39

homolactic fermentation

Question 40

What are the two fates for lactate?

Answer 40

make glucose through gluconeogenesis and can convert back to pyruvate

Question 41

What was the background information of the mice experiment?

Answer 41

tested to see how high fructose corn syrup acted on APC -/- predisposed to cancer mice

Question 42

h