Gluconeogenesis

Question 1

Gluconeogenesis occurs when…

Answer 1

hepatic glycogen is depleted

Question 2

Gluconeogenesis forms glucose from:

Answer 2

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

Question 3

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

Answer 3

Glycolysis

Question 4

The liver converts lactate to pyruvate to glucose which enters the blood. Which pathway is this?

Answer 4

Cori cycle

Question 5

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

Answer 5

Lactate dehydrogenase (LDH)

Question 6

What pathway will turn muscle glucose into pyruvate then alanine entering the blood?

Answer 6

Gluconeogenesis (glucose-alanine cycle)

Question 7

What pathway involves the liver converting alanine to pyruvate then to glucose?

Answer 7

Gluconeogenesis (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

The lumen of the endoplasmic reticulum

Question 13

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

Answer 13

Fructose 1,6-biphosphatase in liver and kidneys

Question 14

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

Answer 14

Glucagon + epinephrine

Question 15

Which two enzymes in gluconeogenesis require ATP?

Answer 15

Pyruvate carboxylase
Phosphoglycerate kinase

Question 16

Which enzyme requires GTP?

Answer 16

PEPCK (phosphoenolpyruvate carboxykinase)

Question 17

List the four enzymes unique to gluconeogenesis

Answer 17

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

Question 18

Which enzyme converts glycerol 3P to DHAP?

Answer 18

Isomerase

Question 19

Which enzyme converts glycerol to glycerol 3P?

Answer 19

Glycerol kinase

Question 20

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

Answer 20

AST/SGOT

Question 21

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

Answer 21

Glutamate dehydrogenase

Question 22

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

Answer 22

Acetyl-CoA buildup via exercise or fasting

Question 23

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

Answer 23

Von Gierke’s

Question 24

What is the location for fructose metabolism?

Answer 24

Liver

Question 25

At what step does fructose enter glycolysis?

Answer 25

Triose phosphate step

Question 26

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

Answer 26

Increased fat production