Chapter 10 Gluconeogenesis

Question 1

what is 1,6-fructobisphosphate inhibited by ?

Answer 1

Phosphofructo kinase

Question 2

PFK- 1 inhibitor

PFK regulator (stimulates PFK-1)

Answer 2

+++ATP and citrate and acetyl CoA

++AMP and LOW ATP

Question 3

Glucagon inhibits

Answer 3

Mechanisms for glycolysis

PFK-2

activates F26bisphosphatase

Question 4

elevated AMP

1. stimulates
2. inhibits

Answer 4

energy-producing (glycolysis)

energy-requiring ones (gluconeogenesis)

Question 5

1. how many reactions are required to convert pyruvate back to free glucose ?
2. how many reactions are irrevrisble ?
3. what are the three irreversible reactions ?
4. what enzymes help the three irreversible ones ?

Answer 5

1. 11 reactions
2. three irreversible reactions
3. hexokinase/glucokinase, PFK-1 and PK
4. glucose-6-phosphatase, fructose 1,6- bisphosphatase Pyruvate Carboxylase and PEPCK

Question 6

less amount of ATP is used in this pathway

6 ATPs are required for this pathway

Answer 6

Glycolyis

Gluconeogenesis

Question 7

PFK - 1

Regulated by stimulation and inhibition

what are the allosteric and hormone regulators

Answer 7

stimulated by low ATP therefore high ADP

inhibited by high ATP

inhibited by citrate

( have to master concept ) stimulated by fructose 6 phosphate

Question 8

inhibitor of Hexokinase

Answer 8

inhibited by glucose-6-phosphate (it’s own product)

Question 9

1. rise in insulin or high levels of insulin means ?
2. rise in glucogon levels mean ?
3. high levels of Insulin is a hormone that favors the breaking down of glucose which is called ?
4. Glucagon is a hormone that inhibits what pathway reaction
5. PFK -1 is stimulated or activated because there is a need for ?

Answer 9

1. there is high glucose levels in the blood
2. there is low glucose levels in the blood
3. Glycolysis
4. Glycolysis
5. breaking down more glucose molecules

Question 10

Inhibitor of 1,6 fructobisphosphate

Answer 10

AMP

Question 11

Glucagon increases transcription of the gene

Answer 11

PEPCK** via transcription factor **cAMP

thereby increasing the availability of this enzyme as levels of it’s substrate rise during fasting

Question 12

a peptide hormone from pancreatic islet alpha cells

Answer 12

Glucagon

Question 13

stimulation of gluconeogenesis by glucagon

Three ways

Answer 13

1. changes in allosteric factors
2. covalent modification
3. induction of enzyme synthesis

Question 14

an example of changes in allosteric factor by stimulating gluconeogenesis is by

Answer 14

glucagon lowering “hepatic: fructose 2,6- bisphosphate by

1. inactivating PFK 2
2. activating Fructose 2,6- Bisphosphatase
3. therefore decreasing concentration of Fructose 2,6Bisphosphate
4. decrease in Fructose 2,6 Bisphosphate inhibits
5. PFK-1

Question 15

slow in response to rapid falling glucose levels

Answer 15

gluconeogenesis

Question 16

Glycerol

Answer 16

• non carbohydrate but ( USED to make energy)
• delivered in the blood to the liver
• hydrolysis TAG in adipose tissue
• phosphorylated by Glycerol Kinase to glycerol-3 phosphate
• oxidized to glycerol-3-phosphate
• oxidized by Glycerol 3 phosphate DH
• becomes DHAP (intermediate in GLYCOLYSIS)