FA synthesis and oxidation

Question 1

Describe carnitine deficiency

Answer 1

Can’t get LCFAs across mitochondrial membrane, so they build up in cytoplasm; can’t use them towards gluconeogenesis or ketogenesis, so you get a hypoketotic hypoglycemia

Question 2

Which ketone cannot be detected in urine?

Answer 2

Beta-hydroxybutyrate

Question 3

Reduced activity of pyruvate carboxylase

Answer 3

Acyl CoA DH deficiency

Question 4

Elevated dicarboxycyclic acid

Answer 4

Acyl CoA DH deficiency

Question 5

Describe acyl CoA dehydrogenase deficiency

Answer 5

Class of enzyme that catalyzes first step of FA oxidation in the mitochondria; buildup of dicarboxycyclic acids + hypoketotic hypoglycemia

Acetyl CoA is also a positive regulator of pyruvate carboxyalse in gluconeogenesis, another cause of hypoglycemia in acyl CoA DH deficiency

Question 6

Elevated LCFA

Answer 6

Carnitine deficiency

Question 7

Steps in FA oxidation

Answer 7

Cytoplasm = FA + CoA –> acyl CoA –> carnitine shuttle

Mitochondria = Acyl CoA –> breakdown into acetyl CoA groups –> TCA cycle or ketogenesis

Question 8

Two causes of hypoketotic hypoglycemia

Answer 8

Acyl CoA dehydrogenase deficiency

Carnitine deficiency

Question 9

Steps in FA synthesis

Answer 9

Citrate in mitochondria –> citrate shuttle across mitochondrial membrane –> citrate in cytoplasm –> ATP citrate lyase –> acetyl CoA –> malonyl CoA –> FA synthesis forms palmitate, a 16C FA

Question 10

Why does starvation or DKA cause ketoacidosis?

Answer 10

Reduced oxaloacetate = decreased TCA cycle and buildup of acetyl CoA = shunts glucose and FFA towards ketogenesis

Question 11

Why does alcoholism cause ketoacidosis?

Answer 11

Depletes NADH, which shunts oxaloacetate towards production of malate, causing buildup of acetyl CoA that shunts glucose and FFA towards ketogenesis