Exam 3 (Cole)

Question 1

Names of the 3 ketone bodies produced in ketogenesis

Answer 1

Acetoacetate, acetone, B-hydroxybutyrate

Question 2

Where does ketogenesis take place?

Answer 2

Mitochondria in the liver

Question 3

What’s the starting substrate of ketogenesis?

Answer 3

Acetyl-CoA

Question 4

Why do we make ketone bodies?

Answer 4

The brain can break them down since they are water-soluble form of lipid derived energy when glucose levels are low

Question 5

Why are ketone bodies formed in uncontrolled type I diabetes?

Answer 5

Oxaloacetate gets used up for gluconeogenesis so acetyl-CoA can no longer be used in the citric acid cycle. Instead it goes to the mitochondria in the liver to create ketone bodies

Question 6

What is the role of carnitine acyltransferases?

Answer 6

Transports fatty acids into the mitochondrial matrix

Question 7

Why are ketone bodies formed in uncontrollable type I diabetes?

Answer 7

Too much glucose in the blood + low insulin causes fatty acids to be dumped into the liver. This causes low-yieldbeta oxidation where acetyl-CoA can no longer be used in the citric acid cycle (too little oxaloacetate) so undergoes ketogenesis. Too many ketone bodies are produced which can cause ketoacidosis

Question 8

What are eicosinoids synthesized from?

Answer 8

Arachadonic acid

Question 9

Which drug inhibits COX1 and COX2 (cyclooxygenase)?

Answer 9

NSAID’s (ibuprofen + asprin)

Question 10

What’s the order of formation for eicosinoids?

Answer 10

Arachidonic acid –> cox1 / cox2 –> prostoglandins / thromboxanes

Question 11

What do COX’s form before they become prostaglandin/thromboxane?

Answer 11

They form ring structures: 5-membered for prostaglandin, 6-membered thromboxane

Question 12

What catalyzes the first step in the synthesis of leukotrienes?

Answer 12

Lipoxygenase

Question 13

What is the role of malonyl-CoA

Answer 13

Inhibits carnitine acyltransferase I

Question 14

Why is the entry of fatty acids into the mitochondria regulated?

Answer 14

If there’s an increase in malonyl CoA, that means that we’re synthesizing fatty acids. If we’re synthesizing, we do not need to break them down for energy so beta-oxidation is shut off

Question 15

What is the product of acetyl-carboxylase in fatty acid synthesis?

Answer 15

Malolnyl-CoA

Question 16

How do acetyl-CoA and NADPH get to the cytoplasm?

Answer 16

Citrate shuttle

Question 17

What is the regulated enzyme in fatty acid synthesis?

Answer 17

Acetyl-CoA carboxylase

Question 18

What does acetyl-CoA carboxylase require in fatty acid synthesis?

Answer 18

Biotin, because it’s a carboxylation reaction which requires 3 things and 1 of them is ATP

Question 19

Does acetyl-CoA carboxylase require ATP?

Answer 19

Yes

Question 20

What is the purpose of fatty acid synthesis?

Answer 20

During a fed state, we store energy by converting acetyl Co-A into fatty acids which can be stored as triglycerides in adipose tissue

Question 21

What is the purpose of hormone-sensitive lipase?

Answer 21

During a fasting state, we break down triglyerides into free fatty acids and glycerol to use as fuel

Question 22

What inhibits hormone sensitive lipase?

Answer 22

Insulin

Question 23

What is the purpose of making malonyl-CoA?

Answer 23

To drive fatty acid synthesis via energy release during condensation and loss of CO2

Question 24

How does citrate relate to fatty acid synthesis?

Answer 24

Citrate is a sign of being well-fed (TCA cycle very active), so it activates acetyl-CoA carboxylase

Question 25

What is the source of acetyl-CoA and NADPH used for fatty acid synthesis?

Answer 25

Citrate

Question 26

What happens to the regulation of acetyl-CoA carboxylase when cAMP levels go up?

Answer 26

Acetyl-CoA carboxylase gets inhibited because high levels of cAMP are a sign of fasted state and we don’t need to be making fatty acids if we’re starving

Question 27

When hormone sensitive lipase is active is acetyl-CoA carboxylase active or inactive?

Answer 27

Inactive

Question 28

Where does beta oxidation occur? What about fatty acid synthesis?

Answer 28

Beta Oxidation occurs in the mitochondria. Fatty acid synthesis occurs in the cytoplasm

Question 29

Is NADH or NADPH used in fatty acid synthesis?

Answer 29

NADPH

Question 30

Is NADH or NADPH a product of beta oxidation?

Answer 30

NADH