Ketones

Question 1

Why can amino acids be used to generate glucose, but fatty acids cannot?

Answer 1

Amino acids can be converted into intermediates on the TCA cycle, then enter into gluconeognesis. Fatty acids however, can only be converted into AcetylCoA, which has no way of entering into gluconeogenesis, because the conversion of pyruvate to AcetylCoA is irreversible (thermodynamically forward reaction).

Exception: odd-chain fatty acids - can be converted into TCA intermediates.

Question 2

What are ketones for?

Answer 2

to prevent protein degradation during times of starvation

Question 3

The liver converts amino acids into what?

Answer 3

glucose and fatty acids

Question 4

What are ketones?

Answer 4

3 water-soluble molecules: acetoacetate, B-hydroxybutarate, and their breakdown product acetone.

Question 5

In which metabolic states are ketones produced?

Answer 5

fasting, carb restrictive diets, prolonged intense exercise, and under/untreated T1DM

Question 6

Where are ketones made? Why are they made from?

Answer 6

in mitochondria of the liver - from fatty acids

Question 7

How are ketones utilized?

Answer 7

they are converted into Acetyl CoA -> TCA -> ATP.

Question 8

What is another way the brain utilizes ketones and why does it need to do this?

Answer 8

turns ketones into fatty acids for greater energy production - does this because fatty acids cannot cross the blood brain barrier

Question 9

What tissues use ketones primarily?

Answer 9

brain, heart, skeletal muscle

Question 10

What do mutation of medium chain fatty acid acyl CoA dehydrogenase cause?

Answer 10

inability to oxidize fatty acids, which leads to fasting hypoglycemia due to lack of available energy from fatty acid breakdown to fuel gluconeogenesis