Glycolysis, Gluconeogenesis and Pentose Phosphate Pathway

Question 1

Which glucose transporter is insulin sensitive?

Answer 1

GLUT 4

Question 2

Where is GLUT 4 found?

Answer 2

Muscle and adipose tissue

Question 3

Where is GLUT 1 found?

Answer 3

Erythrocytes
Endothelial tissue
(Muscle and adipose tissue also)

Question 4

Where is GLUT 2 found?

Answer 4

Liver and pancreas

Question 5

Where is GLUT 3 found?

Answer 5

Brain

Question 6

Where is GLUT 5 found?

Answer 6

Intestines and kidney

Question 7

What reactions occur in glycolysis and in the correct order?

Answer 7

Phosphoryl transfer
Phosphoryl shift
Isomerisation
Dehydration
Aldol cleavage

Question 8

Which intermediate gets split in 2?

Answer 8

Fructose-1,6-bisphosphate

Question 9

List, in order, the intermediates in the investment phase of glycolysis?

Answer 9

Glucose
Glucose-6-phosphate
Fructose-6-phosphate
Fructose-1,6-bisphosphate
Glyceraldehyde-3-phosphate & Dihydroxyacetone phosphate

Question 10

List, in order, the enzymes in the investment phase of glycolysis?

Answer 10

Hexokinase
Phosphohexose isomerase
Phospho fructose kinase-1
Aldolase
Triose phosphate isomerase

Question 11

List, in order, the intermediates in the payoff phase of glycolysis.

Answer 11

Glyceraldehyde-3-phosphate
1,3-bisphosphoglycerate
3-phosphoglycerate
2-phosphoglycerate
Phosphoenolpyruvate
Pyruvate

Question 12

List, in order, the enzymes in the payoff phase of glycolysis?

Answer 12

Glyceraldehyde-3-phosphate dehydrogenase
Phosphoglycerate kinase
Phosphoglycerate mutase
Enolase
Pyruvate kinase

Question 13

What are the enzymes that catalyse irreversible reactions in glycolysis?

Answer 13

Hexokinase
Phosphofructose kinase 1
Pyruvate kinase

Question 14

Which enzymes require the hydrolysis of ATP to complete their functions?

Answer 14

Hexokinase
Phosphofructose kinase 1

Question 15

Which step produces NADH in glycolysis?

Answer 15

Conversion of glyceraldehyde-3-phopshate to 1,3-bisphosphoglycerate by using glyceraldehyde-3-phosphate dehydrogenase

Question 16

Which steps produce ATP?

Answer 16

Conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate by using phosphoglycerate kinase
Conversion of phosphoenolpyruvate to pyruvate by using pyruvate kinase

Question 17

Which enzyme is highly regulated in this pathway?

Answer 17

Pyruvate kinase

Question 18

What is used as a coenzyme during the phosphorylation of glucose?

Answer 18

Mg++

Question 19

Where is the only place that phosphorylation of glucose is reversible?

Answer 19

Liver

Question 20

What is the purpose of phosphorylating glucose?

Answer 20

Lowers intracellular glucose concentration allowing further uptake of glucose

Question 21

What is the primary inhibitor of phosphofructose kinase 1?

Answer 21

High ATP concentrations

Question 22

What is the fate of fructose-6-phosphate if PFK1 is inactivated?

Answer 22

Will be stored as glycogen

Question 23

What intermediates does frucotse-1,6-bisphosphate produce?

Answer 23

Dihydroxyacetone phosphate and glyceraldehyde-3-phosphate

Question 24

Which of the intermediates that fructose-1,6-bisphosphate produces is unable to continue on the glycolysis pathway?

Answer 24

Dihydroxyacetone phosphate

Question 25

Why is the glyceraldehyde-3-phosphate concentration kept low?

Answer 25

To pull the reaction forward along the pathway

Question 26

What does the production of NADH from the oxidation of glyceraldehyde-3-phosphate by glyceraldehyde-3-phosphate dehydrogenase do?

Answer 26

Allows for net production of ATP

Question 27

What is the oxidation of glyceraldehyde-3-phosphate coupled to?

Answer 27

1st production of ATP by phosphoglycerate kinase

Question 28

What coenzymes regulate the activity of pyruvate kinase?

Answer 28

K+ and Mg++

Question 29

What is consumed during the entirety of glycolysis?

Answer 29

1 glucose 2 ATP 2 NAD+

Question 30

What is produced by glycolysis?

Answer 30

2 pyruvate 4 ATP 2 NADH

Question 31

What cleaves glucose from glycogen and starch?

Answer 31

Glycogen phosphorylase

Question 32

What does the cleaving of glucose from glycogen yield?

Answer 32

Glucose-1-phosphate

Question 33

What is the main source of energy in fast twitch muscle fibers?

Answer 33

GLycolysis

Question 34

What does LDH do during anaerobic conditions?

Answer 34

Regenerates NAD+ stores

Question 35

What is a by-product of glycolysis in RBCs?

Answer 35

2,3-diphosphoglycerate

Question 36

Under what conditions do 2,3-diphosphoglycerate concentrations increase?

Answer 36

Hypoxic environments

Question 37

What does 2,3-diphosphoglycerate do?

Answer 37

Promotes release of O2 to tissue when O2 tension and saturation is decreased in lungs

Question 38

What is faster: tumour growth or angiogenesis?

Answer 38

Tumour growth

Question 39

What does the growth of tumours mean in terms of their respiration?

Answer 39

Mostly glycolytic respiration resulting in raised LDH levels

Question 40

Which enzymes regulate the glycolysis pathway?

Answer 40

Hexokinase Phosphofructose kinase 1 Pyruvate kinase

Question 41

Can mammals convert fatty acids to sugars?

Answer 41

No

Question 42

Where does gluconeogenesis occur?

Answer 42

Cytosol of liver cells

Question 43

Is ATP generated during gluconeogensis?

Answer 43

No

Question 44

Why is gluconeogenesis differentially regulated?

Answer 44

to prevent a futile cycle

Question 45

Which enzymes are unique to gluconeogensis?

Answer 45

Pyruvate carboxylase Phosphoenolpyruvate carboxykinase Fructose-1,6-bisphosphatase 1 Glucose 6 phosphatase

Question 46

Where is pyruvate carboxylase found?

Answer 46

Matrix of mitochondria

Question 47

How does oxaloacetate leave the mitochondria?

Answer 47

Converted to PEP or malate

Question 48

How is fructose-1,6-bisphosphatase regulated?

Answer 48

By Phosphofructose kinase 1

Question 49

Where is glucose 6 phosphatase found?

Answer 49

Endoplasmic reticulum

Question 50

What does gluconeogenesis require?

Answer 50

4 ATP 2 GTP 2 NADH

Question 51

When does gluconeogenesis generate glucose?

Answer 51

During starvation Vigorous execise

Question 52

Explain the Cori Cycle.

Answer 52

Glucose gets converted to lactate in muscle Lactate gets converted to glucose in liver

Question 53

What is the role of the Cori Cycle?

Answer 53

Frees muscle from burden of having to produce more energy

Question 54

What is the role of the pentose phosphate pathway?

Answer 54

Formation of pentose phosphate for synthesis of nucleotides

Question 55

What happens to excess pentoses?

Answer 55

Shunted back to glycolysis by conversion to fructose-6-phosphate and glyceraldehyde-3-phosphate

Question 56

Which cells benefit from the pentose phosphate pathway the most?

Answer 56

Cells in which there's a limited need for RNA/DNA synthesis

Question 57

What are the main products of the pentose phosphate pathway?

Answer 57

NADPH and ribose-5-phosphate

Question 58

What are the functions of NADPH?

Answer 58

Electron donor Biosynthesis of fatty acids, cholesterol and steroids Repair of oxidative damage

Question 59

What are the functions of ribose-5-phosphate?

Answer 59

Precursor of nucleotides DNA & RNA synthesis Synthesis of some coenzymes

Question 60

What does the liver use NADPH for?

Answer 60

Hydroxylation(detoxification and excretion of drugs)

Question 61

What is glutathione?

Answer 61

Coenzyme for the protection of the cell against oxidative and chemical insult

Question 62

Where is there more NADPH than ribose-5-phosphate?

Answer 62

Liver and adipose tissue

Question 63

What regulates partitioning into glycolysis versus pentose phosphate pathway?

Answer 63

NADPH (also an antagonist of the system)

Question 64

When can glucose-6-phosphate dehydrogenase be fatal?

Answer 64

During oxidative stress

Question 65

How is glucose-6-phosphate dehydrogenase fatal during oxidative stress?

Answer 65

Impairs NADPH production resulting in haemolysis and creates Heinz bodies in erythrocytes