L6 Gluconeogenesis, Pentose phosphate pathway and Glycogen metabolism

Question 1

Give the definition of Gluconeogensis?

Answer 1

Synthesis of glucose from non-carbohydrate organic precursors

Question 2

How many ATPs does gluconeogenesis consume?

Answer 2

6 ATPs per glucose

Question 3

What is the overall conversion of gluconeogenesis?

Answer 3

2 pyruvates to a glucose

Question 4

What are the four unique enzymes in gluconeogenesis?

Answer 4

(1) Pyruvate carboxylase
(2) Phosphoenolpyruvate (PEP) carboxykinase
(3) Fructose 1,6-bisphosphatase
(4) Glucose 6-phosphatase

Question 5

What is the function of pyruvate carboxylase?

Answer 5

Carboxylates pyruvate to oxaloacetate (OAA), takes up a carbon from CO2

Question 6

What is the function of PEP carboxykinase?

Answer 6

Decarboxylation of OAA to form PEP, release a carbon in the form of CO2

Question 7

What is the function of Fructose 1,6-bisphosphatase?

Answer 7

Release the C-1 phosphoryl group from F1,6-bisphosphate

Question 8

What is the function of Glucose 6-phosphatase?

Answer 8

Releases the C-6 phosphoryl group from G6P

Question 9

Is Fructose 2,6-bisphosphate a metabolite in glycolysis and gluconeogensis?

Answer 9

No

Question 10

Fructose 6-phosphate and fructose 2,6-bisphosphate are interconvertible by what?

Answer 10

A bifunctional enzyme which has both F-2,6-Bpase and PFK-2 activities

Question 11

Fructose 2,6-bisphosphate activates which part and inhibit which part in the bifunctional enzyme?

Answer 11

It activates PFK-1 and inhibits F-1,6-Bpase

Question 12

Raising level of glucagon increases or decreases the F2,6-P level?

Answer 12

Decrease.
And because F2,6-P activates PFK-1 and inhibits F-1,6-Bpase, decrease in F2,6-P promote gluconeogenesis but slows down glycolysis

Question 13

Upon glucagon binding, what is produces?

Answer 13

cAMP

Question 14

PKA is activates by what?

Answer 14

cAMP

Question 15

Activated PKA phosphorylates what?

Answer 15

It phosphorylates the bifunctional enzyme

Question 16

Which of the following cannot be used to make glucose in your body?
A. Alanine
B. Acetyl-CoA
C. Glycerol
D. Lactate

Answer 16

Acetyl-CoA

Question 17

Pentose Phosphate Pathway (PPP) is an alternative oxidation pathway for what metabolite?

Answer 17

Glucose 6-phosphate

Question 18

PPP is usually active in what type of cells and tissues?

Answer 18

In rapidly dividing cells and tissues with active biosynthesis

Question 19

What are the two metabolites generated in PPP?

Answer 19

Ribose 5-phosphate and NADPH

Question 20

What can Ribose 5-phosphate be used for?

Answer 20

Nucleotide biosynthesis

Question 21

What can NADPH be used as?

Answer 21

As reducing power for biosynthesis reactions or protection against oxidative damages

Question 22

What are the two phases in PPP?

Answer 22

Oxidative phase and non-oxidative phase

Question 23

What is the product of the oxidative phase in PPP?

Answer 23

Ribulose 5-phosphate and NADPH

Question 24

What can ribulose 5-phosphate be converted to?

Answer 24

Ribose 5-phosphate

Question 25

What is the main result of the non-oxidative stage of PPP?

Answer 25

Recycling of ribulose 5-P to glucose 6-phosphate

Question 26

What are the two main steps in the non-oxidative stage of PPP?

Answer 26

(1) Isomerization of ribulose 5-phosphate
(2) Rearrangement of carbon skeletons

Question 27

Is the rearrangement of carbon skeletons reversible reactions or irreversible reactions?

Answer 27

Reversible

Question 28

What is the main result of the rearrangement of carbon skeletons phase in the non-oxidative stage of PPP?

Answer 28

Six ribulose 5-P are converted to five glucose 6-P

Question 29

What metabolite is partitioned between glycolysis and pentose phosphate pathway?

Answer 29

Glucose-6-P

Question 30

G6PD is inhibited by which metabolite?

Answer 30

NADPH

Question 31

How many enzymes are needed to release glucose from glycogen?

Answer 31

2 enzymes

Question 32

What are the enzymes needed for releasing glucose from glycogen called?

Answer 32

Glycogen phosphorylase and debranching enzyme

Question 33

What is the function of glycogen phosphorylase?

Answer 33

Releasing the terminal glucose as glucose 1-phosphate

Question 34

Glycogen phosphorylase cannot cleave beyond which point?

Answer 34

point 4 glucose residues upstream of an
α-1, 6 branch point; thus, 4 residues are left on each branch after glycogen phosphorylase finish its function

Question 35

What are the two activities in the debranching enzyme?

Answer 35

(1) 4-α-Glucotransferase activity
- Transfers 3 terminal α-1, 4-linked residues
from a branch to the end of the parent chain

(2) Amylo-1, 6-glucosidase activity
- Cleaves the remaining α-1, 6-linked glucose.

Question 36

Glycogen synthesis begins with which metabolite?

Answer 36

Glucose-6-P

Question 37

What are the 5 steps involved in glycogen synthesis?

Answer 37

(1) Glucose 6-P → Glucose 1-P
(2) Glucose-1-P + UTP → UDP-glucose + pyrophosphate (PPi)
(3) UDP-glucose + Glycogen (n residues) → Glycogen (n+1 residues) + UDP
(4) Amylo-(1,4 →1,6)-transglycosylase (the branching process)

Question 38

What initiates the glycogen synthesis?

Answer 38

Glycogenin

Question 39

Is there any energy change in PPP?

Answer 39

No

Question 40

Is PPP an anabolic pathway or catabolic pathway?

Answer 40

Catabolic pathway;
From (G6P)6C to CO2 and 5C(Ribulose 5-phosphate)

Question 41

Is there any release of CO2 in the PPP pathway?

Answer 41

No

Question 42

What is the respective enzyme of Glucose 6-phosphatase in the Glycolysis?

Answer 42

Hexokinase

Question 43

What is the respective enzyme of Fructose 1,6-bisphosphatase in the Glycolysis?

Answer 43

PFK-1

Question 44

What is the respective enzyme of PKA in Gluconeogensis?

Answer 44

Pyruvate carboxylase and phosphoenolpyruvate (PEP) carboxykinase