Gluconeogenesis

Question 1

What is gluconeogenesis?

Answer 1

Making on new glucose

Question 2

Which organs uses glucose as an energy source?

Answer 2

Brain, testes, erythrocytes and kidney medulla

Question 3

Can glycosis and gluconeogenesis occur at the same time?

Answer 3

No, because its a futile cycle

Question 4

When does glycosis takes place?

Answer 4

In the well fed state, 4-5 hours after a meal

Question 5

When dos gluconeogenesis takes place?

Answer 5

After 4-5 hours in between meals

Question 6

The brain can also get energy from another source

Answer 6

Ketone bodies, after 1-2 weeks without glucose so only under extreme conditions

Question 7

What are the other ways in which the body can get glucose from?

Answer 7

Alpha keto acids, glycerol, lactate and pyruvate,

Question 8

What is the first source of glucose in the body?

Answer 8

Liver, lasts 10- q8 hours in the absence of dietary intake of carbohydrates.

Question 9

What is the second source of glucose?

Answer 9

Gluconeogenesis

Question 10

Gluconeogenesis requires both mitochondrial enzymes and cytosolic enzymes

Answer 10

The first half occurs in the mitochondria while the second half occurs in the cytosol

Question 11

How many enzymes are needed to bypass the 3 rate limiting steps?

Answer 11

4

Question 12

Glycerol, lactate and the alpha keto acids are obtained from

Answer 12

Transamination of glucose amino acids.

Question 13

The first irreversible step in GLYCOSIS is the

Answer 13

Phosphoenolpyruvate to pyruvate by pyruvate kinase

Question 14

What is the enzyme that converts pyruvate to oxaloactate.

Answer 14

Pyruvate carboxykinase

Question 15

Where is carboxylate found

Answer 15

Mitochondria

Question 16

What is the cofactor in the carboxylation of pyruvate?

Answer 16

Biotin. Biotin is bound to apoenzyme of pyruvate carboxylase through an delta amino group of a lysylresidue to form biocytin

Question 17

Can pyruvate come from alanine?

Answer 17

Yes

Question 18

Oxaloactate can not leave the mitochondria so it must be converted to?

Answer 18

Malate by maleate dehydrogenase

Question 19

In the cytosol malate is reoxidised to oxaloactate converted back to PEP by

Answer 19

Phosphoenolpyruvate carboxykinase

Question 20

What is the first bypass state in gluconeogenesis ?

Answer 20

Carboxylation of pyruvate

Question 21

OAA is converted to PEP by

Answer 21

Pep- carboxykinase using hydrolysis of GTP

Question 22

PEP is converted to Fructose 1, 6 bisphosphate by

Answer 22

Glycolytic reactions that occur in the opposite direction in glycosis.

Question 23

What is the allosteric regulator in decarboxylation reaction

Answer 23

Fructose 2,6 phosphate

Question 24

The enzyme fructose 1,6 bisphosphatase used in the conversation of ………………. Instead of the enzyme

Answer 24

Fructose 1,6 bisphosphate to fructose 6 phosphate instead of phosphofructokinase.

Question 25

How is gluconeogenesis regulated?

Answer 25

By energy levels of AMP in the cell, fructose 1,6 bisphosphatase is inhibited and regulator. By fructose 2,6 bisphosphate

Question 26

High levels of ATP is a signal of?

Answer 26

Energy poor state of the cell.

Question 27

Regulation of fructose 2,6 bisphosphate

Answer 27

Fructose 1,6 bisphosphatase is inhibited by fructose 2,6 bisphosphate.

Question 28

Where is the enzyme fructose 2,6 bisphosphate is found?

Answer 28

Liver

Question 29

When epinephrine or glycagon is secreted when happens?

Answer 29

cAMP is produced cAMP dependent protein kinase is activated This phospholates PFK2 and f2,6BPase activity PFK2 is inhibited and F2,6BPase is activated F2,6 breaks down and not inhibit F2,6 Bpass and glycosis is broken down

Question 30

In the absence of epinephrine or glycagon stimulation

Answer 30

cAMP is broken down cAMP dependent protein kinase PFK2 is activated and F2,6BPASE is inactivated F2, 6 BP whose presence stimulates glycosis and inhibits gluconeogenesis .

Question 31

What happens when there are high levels of fructose 2,6 bisphosphate

Answer 31

Activate glycolysis

Question 32

Low levels of fructose 2,6 bisphosphate

Answer 32

Activation of gluconeogenesis

Question 33

What enzyme converts glucose 6 phosphate to glucose

Answer 33

Glucose 6 phosphase , found in the kidney and liver but not muscle like pyruvate carboxylate

Question 34

Can muscles produce glucose by gluconeogenesis

Answer 34

No

Question 35

What disease occurs when there is a deficiency of the enzyme glucose 6 phosphatase ?

Answer 35

glycogen storage disease type 1: Von gierke' disease

Question 36

Type b glycogen 6 phosphate disease is named?

Answer 36

Glucose 6 phosphate translocation deficiency.

Question 37

Glycogen storage diseases

Answer 37

Inherited deficiency of glucose 6 phosphatase characterized by severe fasting hypoglycemia because glucose is unable tobe produced from eo ther gluconeogenesis or glycogenolysis

Question 38

Regulation of gluconeogenesis is determined by the

Answer 38

Circulation of glycagon, availability of gluconeogenesis substrates and allosteric activation by acetyl Co A.

Question 39

Activation by glycagon occurs in two ways

Answer 39

Changes in allosteric effectors ( lowers levels of fructose 2,6 bisphosphate) Covalent modification of enzyme activity ( elevates cAMP levels)

Question 40

Gluconeogenesis rate is affected by availability of precursors especially

Answer 40

Glucose id amino acids

Question 41

Decrease insulin levels mobilize amino acids from muscles to provide

Answer 41

Carbon skeletons for gluconeogenesis

Question 42

What allosteric activates hepatic pyruvate carboxylate during starvation

Answer 42

acteyl CoA

Question 43

What are the sources of glucose

Answer 43

Alfa keto acids , lactate, glycerol found in adipose tissues .

Question 44

What enzyme metabolize glycerol in the liver?

Answer 44

Glycerol kinase , from glycerol to glycerol phosphate

Question 45

Glycerol phosphate is oxidized by glycerol phosphate dehydrogenase to

Answer 45

Dihydroxyacetone

Question 46

Cori cycle

Answer 46

The cycling of lactate and glucose between peripheral tissue and liver

Question 47

Deceive the cori cycle?

Answer 47

Blood borne glucose is converted by exercising muscles to lactate which diffuses in the blood. The liver takes up the lactate and reconverts it to glucose which is released into the normal circulation. Lactate dehydrogenase in the liver converts lactate to oxaloactate to PEP via gluconeogenesis .

Question 48

An increase in alanine in the muscle causes the release of alanine from muscle which will then go to

Answer 48

Into the liver and be converted glucose and then go to the muscle

Question 49

How many ATP are needed to synthesis one mole of glucose from pyruvate in gluconeogenesis ?

Answer 49

12 ATP

Question 50

In step 1 the glycolysis enzyme is .......... While the gluconeogenesis enzyme is

Answer 50

Hexokinase or glucokinase and glucose 6 phosphate

Question 51

Step 3.

Answer 51

Phosphofructokinase ........., fructose 1,6 bisphosphatase

Question 52

Step 9

Answer 52

Pyruvate kinase ......... Pyruvate carboxylase and PEPCk

Question 53

PC is activated by

Answer 53

Acetyl COA and ADP

Question 54

PEP ck synthesis is increased

Answer 54

Glycagon and ADP

Question 55

F 1,6 BPase is inhibited by

Answer 55

f2, 6 BP and AMP

Question 56

F 1,6 BPase

Answer 56

Citrate and glucagon