Fatty Acid Beta Oxidation

Question 1

What happen to FA beta oxidation during fasting?

Answer 1

1. Decreased insulin/glucagon ratio stimulates lipase to free fatty acids from triacylglycerols in adipose tissue
2. FA travel to e requiring tissues (skeletal and heart muscle). Under go B oxidation to produce energy
3. Brain can not use FA as fuel, so liver responds by cleaving glycogen and releasing glucose into the blood.
4. When the liver’s store of glycogen is depleted body resorts to ketone body synthesis

Question 2

What is ketone body synthesis?

Answer 2

1. Increased Fatty acid beta oxidation in the liver results in NADH and acytl CoA
2. Elevated NADH drives TCA backwarts–oxaloacetate is converted to malate. Malate leaves TCA for gluconeogenesis.
3. Reduction of oxaloacetate diverts acetyl CoA to ketone body syntehsis rather than TCA cycle.

Question 3

What is ketoacidosis?

Answer 3

1. The depression of blood pH by excessive ketone body production
2. caused by starvation or diabetes

Question 4

What happens in the break down of ODD chain length fatty acids?

Answer 4

1. Beta oxidation occurs until the chain is 5 C long

2. Thiolase makes one molecule of acetyl CoA (TCA cycle) and one molecule propionyl CoA (TCA cycle anaplerotic)

Question 5

What happens to branched chain fatty acids?

Answer 5

Broken down in peroxisomes, similar to long chain fatty acids. First the alpha C is oxidized to CO2 then B oxidation occurs releasing propionyl CoA and ACetyl CoA

Question 6

What happens to unsaturated FA?

Answer 6

Most dietary unsaturated fats have cis double bonds but enoyl coA hydratase can only accept substrates with trans. Enoyl CoA isomerase converts cis to trans configutaition.

Question 7

What happens in peroxisomal oxidation?

Answer 7

Long fatty acid chains are degraded in peroxisomes. First step produces H2O2. Beta oxidation continues until chains are reduced to 4-6 C. Short fatty acids are then transferred to mitochondria for complete b oxidation. Enter thorugh carnitine transport.