Gluconeogenesis

Question 1

what is the definition of gluconeogenesis?

Answer 1

make glucose from non-CHO

Question 2

Gluconeogenesis occurs when…

Answer 2

hepatic glycogen is depleted

Question 3

Gluconeogenesis forms glucose from:

Answer 3

• Lactic acid from muscle and RBC (Cori cycle)
• Amino acids from muscle protein
• Glycerol released from triglycerides in adipose tissue

Question 4

Name the pathway that converts glucose to pyruvate to lactate which leaves the tissue

Answer 4

Glycolysis

Question 5

What is the name of the pathway in the liver that converts lactate to pyruvate to glucose which enters the blood?

Answer 5

Cori cycle

Question 6

What is the enzyme that converts pyruvate to lactate in the liver?

Answer 6

Lactate dehydrogenase (LDH)

Question 7

Name the pathway:
muscle glucose -> pyruvate -> alanine entering the blood
Liver alanine -> pyruvate -> glucose

Answer 7

glucose-alanine cycle

Question 8

What is the enzyme that converts alanine to pyruvate in the liver?

Answer 8

ALT/SGPT

Question 9

For gluconeogenesis, how many ATP per pyruvate are required to generate one glucose?

Answer 9

Require 4 ATP per pyruvate

Question 10

Which pathway provides the ATP needed for gluconeogenesis?

Answer 10

Beta oxidation of fats

Question 11

Where in the cell does gluconeogenesis begin?

Answer 11

Mitochondria

Question 12

Where in the cell does gluconeogenesis end?

Answer 12

cytoplasm
(lumen of endoplasmic reticulum)

Question 13

What is the allosteric enzyme of gluconeogenesis? Where is it?

Answer 13

pyruvate carboxylase
mitochondria

Question 14

What hormone(s) activates Fructose 1,6-biphosphatase?

Answer 14

Glucagon + epinephrine

Question 15

what other pathway is also activated by epinephrine and glucagon?

Answer 15

lipolysis & beta-oxidation of fats

Question 16

Which two enzymes in gluconeogenesis require ATP?

Answer 16

Pyruvate carboxylase
Phosphoglycerate kinase

Question 17

Which enzyme requires GTP?

Answer 17

PEPCK (phosphoenolpyruvate carboxykinase)

Question 18

List the four enzymes unique to gluconeogenesis

Answer 18

1. Pyruvate carboxylase
2. PEPCK
3. Fructose biphosphatase
4. Glucose 6 phosphatase (liver only)

Question 19

Which enzyme converts glycerol 3P to DHAP?

Answer 19

Isomerase

Question 20

Which enzyme converts glycerol to glycerol 3P?

Answer 20

Glycerol kinase

Question 21

Which enzyme will allow aspartate/asparagine into the Kreb’s cycle?

Answer 21

AST/SGOT

Question 22

Which enzyme will allow glutamate/glutamine into the Kreb’s cycle?

Answer 22

Glutamate dehydrogenase

Question 23

what is the mechanism for decreasing pyruvate dehydrogenase and increasing pyruvate carboxylase during gluconeogenesis?

Answer 23

acetyl-CoA buildup via exercise or fasting

Question 24

what is the name of the genetic disease where the enzyme glucose 6 phosphatase is missing?

Answer 24

Von Gierke’s

Question 25

what is the location for fructose metabolism?

Answer 25

liver

Question 26

at what step does fructose enter glycolysis?

Answer 26

triose phosphate step

Question 27

what is the impact of high levels of fructose in the diet?

Answer 27

increased fat production