M1: Gluconeogenesis L5

Question 1

What is gluconeogenesis?

Answer 1

The biosynthesis of new glucose from non-carbohydrate sources.

Question 2

When does gluconeogenesis occur? And why does it occur during this time?

Answer 2

When fasting…

1. dietary glucose is not available
2. exhaustion of intracellular glucose
3. glycogen pool in liver is depleted
4. blood glucose levels are about to go below normal

Question 3

In what organs does gluconeogenesis occur?

Answer 3

Liver (major) & kidney (minor)

Question 4

What is the starting point of gluconeogenesis?

Answer 4

Oxaloacetate

Question 5

What are the possible substrates of gluconeogenesis?

Answer 5

1. Lactate
2. Pyruvate
3. Intermediates of the CAC
4. Amino acids

Question 6

Draw the gluconeogenesis reaction starting from pyruvate. (even tho the starting point is technically oxaloaetate)

Answer 6

See lecture 5.1 slide 39

Question 7

What regulates pyruvate carboxylase and how?

Answer 7

Acetyl-CoA allosterically activates pyruvate carboxylase.

Question 8

What regulates PEPCK and how?

Answer 8

In a shortage of glucose, more PEPCK will be made. Controlled by transcriptional regulation.

Question 9

What does it cost to make 1 glucose from 2 pyruvates?

Answer 9

It costs 4ATP, 2GTP, 2NADH to synthesize 1 glucose.