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Biochem Test II > Lipids II > Flashcards

Lipids II Flashcards

1
Q

What two molecules does alcohol metabolism produce?

A

acetyl-CoA and NADH

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2
Q

What is the main function of the citrate cleavage pathway?

A

to export excess acetyl-CoA from the liver

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3
Q

What is the function of ATP-citrate lyase?

A

to cleave citrate into OAA and acetyl-CoA

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4
Q

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

A

Pyruvate

Malate Dehydrogenase: OAA to Malate

Malic Enzyme: Malate to Pyruvate

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5
Q

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

A

pyruvate carboxylase

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6
Q

What does fatty acid synthesis begin with?

A

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

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7
Q

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

A

formation of malonyl-CoA

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8
Q

What is the substrate for fatty acid synthase?

A

malonyl-CoA

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9
Q

Where does elongation of FAs occur?

A

endoplasmic reticulum or mitochondria

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10
Q

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

A

Malonyl CoA

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11
Q

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

A

acetyl-CoA

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12
Q

Where does elongation of FAs occur?

A

at the beta-carbon

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13
Q

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

A

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

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14
Q

At what number carbon is a double-bond introduced?

A

carbon #9

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15
Q

Where can further de-saturases introduce double bonds?

A

carbons 5 and 6

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16
Q

What is the suructural protein that surrounds fats?

A

perilipin

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17
Q

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

A

glycerol.

DHAP is converted to glycerolphosphate by glycerol phosphate dehydrogenase

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18
Q

What is the backbone of FA synthesis?

A

glycerol-3-phosphate

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19
Q

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

A

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

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20
Q

What is the first contributing molecule in fat synthesis?

A

Stearoyl-CoA

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21
Q

What is the first intermediate molecule in TAG synthesis?

A

Lysophosphatidic acid

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22
Q

What is the second contributing molecule in TAG synthesis?

A

Oleoyl-CoA

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23
Q

What is the 2nd intermediate molecule in TAG synthesis?

A

Phosphatidic Acid

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24
Q

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

A

Phosphatidate Phosphatase

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25
Q

What is the third contributing molecule to TAG synthesis?

A

Palmitoyl-CoA

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26
Q

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

A

insulin/glucagon

AMP/ATP

PPAR

27
Q

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

A

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

28
Q

What two enzymes are activated by citrate?

A

FA synthase and acetyl-CoA carboxylase

29
Q

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

A

PKA inactivates acetyl-CoA carboxylase

30
Q

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

A

AMP-dependent kinase. inactivates acetyl-CoA Carboxylase.

31
Q

What intermediate of FA synthesis shuts down FA degradation?

A

Malonyl-CoA

32
Q

What is the main regulated step of FA degradation?

A

Import of FAs into the mitochondrion by CPT I

33
Q

Specifically, how does malonyl-CoA inhibit FA degradation?

A

malonyl-CoA inhibits the activity of CPT I

34
Q

What activates peroxisome proliferator-activated receptor (PPAR)?

A

free fatty acids

35
Q

What does PPAR do?

A

txn activator of genes promoting FA oxidation and ketogenesis

36
Q

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

A

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

37
Q

What activates hormone sensitive lipase?

A

PKA

38
Q

What component of TAGs can PKA activate?

A

perilipin

39
Q

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

A

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

40
Q

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

A

beta-hydroxyacyl dehydrogenase requires NAD to function

lack of NAD slows down FA degradation

41
Q

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

A

damaged liver can not export VLDLs

42
Q

How does the liver export FAs?

A

via VLDLs

43
Q

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

A

acetyl-CoA and OAA

44
Q

What enzyme cleaves citrate?

A

ATP-citrate lyase

45
Q

What does ATP-citrate lyase cleave citrate into?

A

acetyl-CoA and OAA

46
Q

What is the function of malic enzyme?

A

malate to pyruvate

47
Q

How does pyruvtae get into the mitochondrial matrix?

A

a specific translocase

48
Q

What reducing equivalent does malic enzyme produce?

A

NADPH

49
Q

What is the substrate for FA synthase?

A

malonyl-CoA

50
Q

Where does the elongation of FAs occur?

A

mitochondria or ER

51
Q

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

A

ER = malonyl-CoA

mito = acetyl-CoA

52
Q

Where does FA elongation occur?

A

carboxyl-CoA

53
Q

Where does FA desaturation occur?

A

ER

54
Q

What enzyme does FA desaturation require?

A

p450 monooxygenase

55
Q

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

A

carbon 9

56
Q

What is the function of glycerol phosphate dehydrogenase?

A

to convert DHAP into glycerol-3-phosphate

57
Q

What enzyme of FA synthesis does insulin induce?

A

acetyl-CoA carboxylase

58
Q

What enzymes of FA synthesis are activated by citrate?

A

fatty acid synthase and acetyl-CoA carboxylase

59
Q

What is the main regulated step of FA degradation?

A

import into the mitochondria by CPT-I

60
Q

What intermediate of FA synthesis shuts down CPT-I?

A

Malonyl-CoA

61
Q

How is HSL regulated via phosphorylation?

A

When phosphorylated, HSL is actively exporting FAs

62
Q

How does PKA affect lipid droplets?

A

activates perilipin

63
Q

How do low levels of energy inhibit fatty acid synthesis?

A

AMP-dependent kinase inactivates acetyl-CoA Carboxylase

Biochem Test II (14 decks)

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