1.8 - Fatty Acid Metabolism I

Question 1

how many mol of ATP does one molecule of glucose produce?

Answer 1

32

Question 2

how many mol of ATP does one molecule of palmitate produce?

Answer 2

106

Question 3

what does a fatty acid molecule always contain (2)

Answer 3

1. long hydrocarbon chain; alkyl group
2. terminal carboxylate group

Question 4

fatty acid solubility (2)

Answer 4

1. insoluble in water
2. soluble in organic solvent

Question 5

structure of the fatty acid palmitate (2)

Answer 5

1. 15 hydrocarbon chain; alkyl group
2. terminal carboxylate group

Question 6

fatty acid activation (2)

Answer 6

1. FA + ATP -> Acyl adenylate
2. Acyl adenylate + CoA -> Acyl CoA

Question 7

action of Acyl CoA synthetase in fatty acid activation (2)

Answer 7

1. catalyses covalent attachment of a phosphoryl group of ATP (AMP) to oxygen molecule of fatty acid carboxylate group
   - yields acyl adenylate intermediate
2. replaces AMP molecule of acyl adenylate with sulfhydryl group of CoA
   - gives one of each acyl-CoA and AMP

Question 8

what enzyme catalyses fatty acid activation?

Answer 8

Acyl CoA synthetase

Question 9

Ketone body formation

Answer 9

3 acetyl CoAs joined to form ketone bodies

Question 10

molecules fuelling formation of ketone bodies (2)

Answer 10

1. acetoacetate
2. 6-hydroxybutyrate

Question 11

what happens to the ketone body acetone

Answer 11

lost in breath/sweat/urine, not respired

Question 12

metabolic state leading to ketone body formation(2)

Answer 12

1. under conditions of prolonged fasting or diabetes oxaloacetate consumed to form glucose
2. reduces availability of oxaloacetate in TCA cycle resulting in accumulation of acetyl-CoA

Question 13

how does accumulation of acetyl-CoA result in ketone bodies being made

Answer 13

when acetyl-CoA builds up in liver beyond capacity of TCA cycle to consume it, ketone bodies are made

Question 14

role of ketone bodies

Answer 14

released into blood and used as fuel by other cells especially in cardiac muscle cells and renal cortex

Question 15

why do heart muscle and renal cortex cells use ketone bodies instead of glucose? (2)

Answer 15

1. glucose important for muscles and brain
2. used in order to not waste glucose

Question 16

ATP mol produced in one round of TCA cycle

Answer 16

10

Question 17

mol ATP produced from one molecule of glucose by glycolysis

Answer 17

2

Question 18

fatty acid catabolism summary (2)

Answer 18

1. 2 carbons in form of acetyl-CoA removed from FA in every cycle of B-oxidation
2. 1 molecule each NADH and FADH2 released in every cycle of B-oxidation yielding 4 molecules of ATP per cycle

Question 19

degradation of unsaturated fatty acids (3)

Answer 19

1. mono-unsaturated FA (such as palmitoleate) transported across mitochondrial inner membrane (just like saturated palmitate)
2. on mitochondrial outer membrane, palmitoleate activated with ATP and CoA by acyl CoA synthetase to give palmitoleoyl CoA
3. palmitoleoyl CoA undergoes 3 round B oxidation inside mitochondria

Question 20

odd-chain FA

Answer 20

FA with odd-number carbons

Question 21

degradation of odd-chain FA (2)

Answer 21

1. end up with 3 carbon CoA (propionyl CoA)
2. propionyl CoA enters TCA cycle after being converted to succinyl CoA