Lipids II

Question 1

What two molecules does alcohol metabolism produce?

Answer 1

acetyl-CoA and NADH

Question 2

What is the main function of the citrate cleavage pathway?

Answer 2

to export excess acetyl-CoA from the liver

Question 3

What is the function of ATP-citrate lyase?

Answer 3

to cleave citrate into OAA and acetyl-CoA

Question 4

What does OAA need to be converted to in order to enter the mitochondrial matrix? What enzymes are responsible for this?

Answer 4

Pyruvate

Malate Dehydrogenase: OAA to Malate

Malic Enzyme: Malate to Pyruvate

Question 5

In the citrate cleavage pathway, what enzyme is responsible for converting pyruvate into OAA?

Answer 5

pyruvate carboxylase

Question 6

What does fatty acid synthesis begin with?

Answer 6

carboxylation of acetyl-CoA to malonyl-CoA by acetyl-CoA carboxylase

Question 7

What is the committed, regulated step of fatty acid synthesis?

Answer 7

formation of malonyl-CoA

Question 8

What is the substrate for fatty acid synthase?

Answer 8

malonyl-CoA

Question 9

Where does elongation of FAs occur?

Answer 9

endoplasmic reticulum or mitochondria

Question 10

What is the carbon donor for the elongation of FAs in the ER?

Answer 10

Malonyl CoA

Question 11

What is the carbon donor for the elongation of FAs in the mitochondria?

Answer 11

acetyl-CoA

Question 12

Where does elongation of FAs occur?

Answer 12

at the beta-carbon

Question 13

Where does de-saturation of FAs occur? What enzyme is responsible for this?

Answer 13

desaturation occurs in the ER. The enzyme responsible is p450 mono-oxygenase

Question 14

At what number carbon is a double-bond introduced?

Answer 14

carbon #9

Question 15

Where can further de-saturases introduce double bonds?

Answer 15

carbons 5 and 6

Question 16

What is the suructural protein that surrounds fats?

Answer 16

perilipin

Question 17

What metabolic intermediate is required for fatty acid synthesis? What enzyme produces this intermediate?

Answer 17

glycerol.

DHAP is converted to glycerolphosphate by glycerol phosphate dehydrogenase

Question 18

What is the backbone of FA synthesis?

Answer 18

glycerol-3-phosphate

Question 19

What must occur before acyl molecules are bound toglycerol-3-phosphate?

Answer 19

They must be bound to CoA in an ATP-dependent manner

Question 20

What is the first contributing molecule in fat synthesis?

Answer 20

Stearoyl-CoA

Question 21

What is the first intermediate molecule in TAG synthesis?

Answer 21

Lysophosphatidic acid

Question 22

What is the second contributing molecule in TAG synthesis?

Answer 22

Oleoyl-CoA

Question 23

What is the 2nd intermediate molecule in TAG synthesis?

Answer 23

Phosphatidic Acid

Question 24

What is the enzyme that converts phosphatidic acid to 1,2-diacylglycerol?

Answer 24

Phosphatidate Phosphatase

Question 25

What is the third contributing molecule to TAG synthesis?

Answer 25

Palmitoyl-CoA

Question 26

What are the three major contributors to fatty acid synthesis or fatty acid degradation?

Answer 26

insulin/glucagon AMP/ATP PPAR

Question 27

In relation to FA metabolism, what does insulin increase the expression of?

Answer 27

Acetyl-CoA carboxylase, malic enzyme, FA synthase and G6P dehydrogenase

Question 28

What two enzymes are activated by citrate?

Answer 28

FA synthase and acetyl-CoA carboxylase

Question 29

What are the relation of PKA to acetyl-CoA carboxylase?

Answer 29

PKA inactivates acetyl-CoA carboxylase

Question 30

What enzyme in directly activated by AMP? What does this kinase do in relation to FA synthesis?

Answer 30

AMP-dependent kinase. inactivates acetyl-CoA Carboxylase.

Question 31

What intermediate of FA synthesis shuts down FA degradation?

Answer 31

Malonyl-CoA

Question 32

What is the main regulated step of FA degradation?

Answer 32

Import of FAs into the mitochondrion by CPT I

Question 33

Specifically, how does malonyl-CoA inhibit FA degradation?

Answer 33

malonyl-CoA inhibits the activity of CPT I

Question 34

What activates peroxisome proliferator-activated receptor (PPAR)?

Answer 34

free fatty acids

Question 35

What does PPAR do?

Answer 35

txn activator of genes promoting FA oxidation and ketogenesis

Question 36

Specifically, how does the insulin/glucagon ratio affect FA release from adipose tissue?

Answer 36

a high glucagon/insulin ratio leads to release of FAs from adipose tissue

Question 37

What activates hormone sensitive lipase?

Answer 37

PKA

Question 38

What component of TAGs can PKA activate?

Answer 38

perilipin

Question 39

What is the first factor of why alcohol consumption can contribute to the development of fatty liver in chronic alcoholism?

Answer 39

High NADH (as generated by alcohol consumption) blocks CAC enzymes and forces acetyl-CoA into FA synthesis

Question 40

What is the second factor of why alcohol consumption can contribute to the development of fatty liver in chronic alcoholism?

Answer 40

beta-hydroxyacyl dehydrogenase requires NAD to function | lack of NAD slows down FA degradation

Question 41

What is the third factor of why alcohol consumption can contribute to the development of fatty liver in chronic alcoholism?

Answer 41

damaged liver can not export VLDLs

Question 42

How does the liver export FAs?

Answer 42

via VLDLs

Question 43

What two products form in the citrate cleavage pathway to make citrate?

Answer 43

acetyl-CoA and OAA

Question 44

What enzyme cleaves citrate?

Answer 44

ATP-citrate lyase

Question 45

What does ATP-citrate lyase cleave citrate into?

Answer 45

acetyl-CoA and OAA

Question 46

What is the function of malic enzyme?

Answer 46

malate to pyruvate

Question 47

How does pyruvtae get into the mitochondrial matrix?

Answer 47

a specific translocase

Question 48

What reducing equivalent does malic enzyme produce?

Answer 48

NADPH

Question 49

What is the substrate for FA synthase?

Answer 49

malonyl-CoA

Question 50

Where does the elongation of FAs occur?

Answer 50

mitochondria or ER

Question 51

What is the difference in carbon donor between ER and mitochondria relating to FA synthesis?

Answer 51

ER = malonyl-CoA mito = acetyl-CoA

Question 52

Where does FA elongation occur?

Answer 52

carboxyl-CoA

Question 53

Where does FA desaturation occur?

Answer 53

ER

Question 54

What enzyme does FA desaturation require?

Answer 54

p450 monooxygenase

Question 55

Where is the double-bond introduced for desaturation of FAs?

Answer 55

carbon 9

Question 56

What is the function of glycerol phosphate dehydrogenase?

Answer 56

to convert DHAP into glycerol-3-phosphate

Question 57

What enzyme of FA synthesis does insulin induce?

Answer 57

acetyl-CoA carboxylase

Question 58

What enzymes of FA synthesis are activated by citrate?

Answer 58

fatty acid synthase and acetyl-CoA carboxylase

Question 59

What is the main regulated step of FA degradation?

Answer 59

import into the mitochondria by CPT-I

Question 60

What intermediate of FA synthesis shuts down CPT-I?

Answer 60

Malonyl-CoA

Question 61

How is HSL regulated via phosphorylation?

Answer 61

When phosphorylated, HSL is actively exporting FAs

Question 62

How does PKA affect lipid droplets?

Answer 62

activates perilipin

Question 63

How do low levels of energy inhibit fatty acid synthesis?

Answer 63

AMP-dependent kinase inactivates acetyl-CoA Carboxylase