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Biochemistry > Lipids > Flashcards

Lipids Flashcards

1
Q

____ and ___ fatty acidsare sufficiently soluble to pass through the intestinal epithelial cells to enter the circulation without being incorporated into triglycerides.

A

Medium and short-chain fatty acids

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2
Q

_____ digests TG to 2-monoacyglycerols and FFA which are packaged into micelles

A

pancreatic lipase

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3
Q

FA from the micelles are activated by this enzyme to form fatty acyl-CoA

A

fatty acyl-CoA synthetase (thiokinase)

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4
Q

The regulatory enzyme acetyl-CoA carboxylase is inhibited by phosphorylation by this enzyme

A

AMP-activated protein kinase (not protein kinaseA)

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5
Q

A fat synthesis enzyme that is activated by dephosphorylation, by citrate and insulin

A

acetyl CoA carboxylase

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6
Q

This provides 2 carbon units that add to palmitoyl-CoA to elongate the FA

A

malonyl CoA

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7
Q

Location (carbon) at which human can introduce double bonds

A

Carbon 5,6,9

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8
Q

The major sources of essential FA required in the human diet. This is used for the synthesis of arachindonic acid.

A

Linoleate (18:2, delta 9,12) and a-linolenate (18:3 delta 9,12,15)

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9
Q

Adipose tissue cannot generate G3P from glycerol because it lacks this enzyme

A

glycerol kinase

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10
Q

Phospholipids are synthesized from

A

phosphatidic acid

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11
Q

Inhibition of this enzyme prevents newly synthesized fatty acids from entering the mitochondria

A

carnitine acyltransferase I

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12
Q

This apolipoprotein activates lipoprotein lipase. This is transferred from HDL to chylomicrons and VLDL

A

Apo CII

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13
Q

The key intermediates of cholesterol synthesis are ___, ___, ____, and ____.

A

HMG-CoA, mavelonic acid, isopentenyl pyrophosphate, and squalene

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14
Q

___ and ___ are major carriers of triglyceride.

A

Chylomicrons and VLDL. TG are degraded by lipoprotein lipase. In terms of density, chylomicrons < VLDL.

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15
Q

Cholesterol obtained by HDL is converted to cholesterol esters by this reaction.

A

LCAT reaction which is activated by ApoAI

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16
Q

The liver lacks this enzyme thus it cannot use ketone bodies as energy source.

A

succiny-CoA-acetoacetate-CoA transferase (a thiotransferase)

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17
Q

Oleic acid has how many double bonds?

A

One double bond

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18
Q

What is the trans form of oleic acid

A

Elaidic acid

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19
Q

What is the end product of mammalian FA synthesis?

A

palmitic acid

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20
Q

What is the predominant FA in olive oil

A

Oleic acid

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21
Q

What are your essential FA

A
  1. Linoleic

2. Linolenic acid

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22
Q

____ is an essential fatty acid with 2 double bonds

A

Linoleic acid

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23
Q

___ is an essential fatty acid with 3 double bonds

A

Linolenic acid

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24
Q

Arachidonic acid can be derived in what essential fatty acid?

A

linoleic acid

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25
Q

Fatty acid that may increase the risk of prostate and colon cancer

A

Staurated FA

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26
Q

FA associated with decreased risk of coronary heart disease, decrease sudden cardiac death, lower BP, decrease tendencies for thrombosis

A

omega 3 FA = linolenic

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27
Q

provide arachidonic acid which is an important precursor of prostaglandins and leukotrienes

A

omega 6 FA = linoleic

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28
Q

[Fatty Acid activation]

What enzyme activates fatty acid so that it can participate in metabolic process? (happens in the cytosol)

A
  1. Fatty acyl CoA synthetase
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29
Q

[Lipogenesis]

What is the immediate substrate of for lipogenesis?

A

Acetyl CoA

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30
Q

[Lipogenesis]

What is the product?

A

palmitoyl CoA

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31
Q

[Lipogenesis]

What is the rate-limiting step?

A

AcetylCoa + HCO3 + ATP to Malonyl CoA

via Acetyl CoA carboxylase

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32
Q

How will you transport Acetyl CoA to the cytosol?

A

via the citrate shuttle

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33
Q

Citrate outside the cytosol is converted to oxaloacetate and acetyl CoA via this enzyme

A

ATP-citrate lyase

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34
Q

Acetyl CoA in the cytosol is converted to malonyl CoA via this enzyme

A

Acetyl CoA carboxylase

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35
Q

What inhibits acetyl CoA carboxylase?

A

Glucagon and epinephrine

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36
Q

What enzyme is needed to elongate the fatty acid?

A

Fatty acid synthase

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37
Q

What is the primer needed by the fatty synthase enzyme to create palmitoyl CoA?

A

Acetyl CoA

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38
Q

After the primer acetyl CoA, what carbon units are subsequently added to elongate the fatty acid?

A

malonyl CoA

39
Q

What are the steps in FA elongation that is repeated 7x?

A
  1. Condensation
  2. Reduction
  3. Dehydration
  4. Reduction

CRDR

40
Q

What is the role of NADPH in fatty acid synthesis?

A

required as donor of reducing equivalents in both reduction reactions

41
Q

Fatty acid elongation happens in which part of the cell

A

Smooth Endoplasmic Reticulum

42
Q

[Synthesis of TAG]

How will you synthesize TAG?

A
  1. Sequential addition of two fatty acyl CoA to G3P
  2. Removal of phosphate
  3. Addition of third fatty acyl CoA
43
Q

Where will you source glycerol 3 phosphate?

A
  1. DHAP from glycolysis

2. Phosphorylation of free glycerol

44
Q

What enzyme phosphorylates free glycerol which happens in the liver only?

A

Glycerol kinase

45
Q

what enzyme converts DHAP to G3P?

A

glycerol-3-dehydrogenase

Needs NADH
Happens in liver and adipose tissue

46
Q

What activates hormone sensitive lipase?

A
  1. low insulin
  2. high epinephrine
  3. high cortisol
47
Q

Conversion of glycerol to glucose is activated by what hormones?

A
  1. Increase in glucagon

2. Increase in cortisol

48
Q

What hormone is active during a fasting state which hydrolyzes TAG to FA and glycerol

A

Hormone-sensitive lipase

  1. low insulin
  2. High epinephrine
  3. High cortisol
49
Q

Hormone sensitive lipase removes fatty acid in what carbons?

A

Carbon 1 and Carbon 3

50
Q

What are the products of beta-oxidation?

A
  1. acetyl Coa

2. NADH and FADH2

51
Q

What are the fates of AcetylCoA from beta oxidation?

A
  1. enters the citric acid cycle
  2. Cholesterol synthesis
  3. Ketone body metabolsm
52
Q

Fatty acid activation occurs where?

A

cytosol

53
Q

Beta oxidation occurs where?

A

mitochondria

54
Q

What is substrate of beta oxidation?

A

palmitate

55
Q

What are the products of beta oxidation

A
  1. 8 acetyl CoA
  2. 7 NADH
  3. 7 FADH2
56
Q

What is the rate limiting step of beta oxidation?

A

Translocation of fatty acyl CoA from the cytosol to the mitochondria

via Carnitine-palmitoyl transferase

57
Q

What enzyme activates fatty acid to transport fatty acid to the mitochondria?

A

Fatty acyl synthetase

58
Q

How will you transport fatty acyl CoA to the mitochondria?

A
  1. Activate fatty acid
  2. Attach carnitine to activated fatty acyl in the outer mitochondrial membrane via the enzyme carnitine acyltransferase -1
  3. Fatty acyl-carnitine is shuttled through the inner membrane
  4. Carnitine acyltransferase-2 transfers fatty acyl group back to a CoA in the mitochondrial matrix
59
Q

What are the enzymes included in fatty acid oxidation?

A
  1. Fatty acyl CoA dehydrogenase
  2. delta 2 enol CoA hydratase
  3. 3-hydroxyacyl-CoA dehydrogenase
  4. Thiolase
60
Q

Each cycle of Fatty acyl CoA yields?

A
  1. FADH2
  2. NADH
  3. AcetylCoA

Repeated 7x

61
Q

What are the steps in fatty acyl CoA breakdown?

A

OHOT

  1. Oxidation
  2. Hydration
  3. Oxidation
  4. Thiolysis
62
Q

1 unit palmitate yields how many ATPs?

A

106 ATPs

63
Q

Oxidation of fatty acid with an odd number will yield what byproducts?

A
  1. Acetyl Coa

2. Propionyl CoA

64
Q

What is the fate of propionyl Coa after undergoing breakdown??

A

Converted to succinyl CoA (used in TCA)

65
Q

What is the intermediate product of propionyl before it is converted to succinyl Coa?

A

Methylmalonyl CoA

66
Q

Propionyl CoA is converted to methylmalonyl CoA via this enzyme

A

Propionyl-CoA carboxylase

needs biotin

67
Q

Methylmalonyl CoA is converted to Succinyl CoA via this enzyme

A

Methylmalonyl-CoA mutase

needs B12

68
Q

___ oxidize very long chains of FA

A

peroxisome

69
Q

What enzyme is required to oxidize unsaturated FA

A

3,2 enoyl-CoA isomerase

70
Q

[diagnosis]

ichthyosis, hair loss, poor wound healing, visual, neurologic abnormalities

A

deficiency of EFA

71
Q

[diagnosis]

hypoglycemia due to impaired fatty acid oxidation, lipid accumulation and muscular weakness,

patient undergoing hemodialysis

A

Carnitine deficiency

72
Q

[diagnosis: CPT I or CPT II]

reduced FA oxidation leading to hypoglycemia, coma and death

A

carnitine-palmitoyl transferase I deficiency

73
Q

[diagnosis: CPT I or CPT II]

cardiomyopathy, muscle weakness with myoglobinemia after prolonged exercise, affect cardiac and skeletal muscle

A

Carnitine-palmitoyl transferase II deficiency

74
Q

What is the most common inborn error of FA oxidation?

A

Medium Chain Fatty acyl CoA dehydrogenase deficiency

75
Q

[diagnosis]

severe hypoglycemia, accumulation of dicarboxylic acids in the urine

A

MCAD

76
Q

[diagnosis]

caused by eating the unripe fruit of akee tree

A

Jamaican vomiting sickness

77
Q

What toxin is seen in the unripe fruit of akee tree?

A

hypoglycin

78
Q

What is the MOA of hypoglycin (from unripe fruit of akee tree)

A

Inactivates medium and short chain Acyl CoA dehydrogenase inhibiting beta oxidation and causing hypoglycemia

79
Q

[diagnosis]

deficiency of phytanoyl-CoA hydroxylase leads to accumulation of phytanic acid

A

refsum disease

80
Q

[diagnosis]

peripheral neuropathy, ataxia, retinitis pigmentosa, abnormal skin and bone

A

refsum disease

81
Q

[diagnosis]

____ syndrome is an inherited absence of peroxisome in all tissues; can lead to cerebrohepatorenal syndrome

A

Zellweger syndrome

82
Q

[diagnosis]

mental retardation, weakness, hypotonia, craniofacial dysmorphism, liver dysfunction with jaundice

A

Zellweger syndrome

83
Q

[diagnosis]

inability to transport VLCFA across the peroxisomal membrane leading to accumulation in the brain, adrenals, and testes

A

Adrenoleukodystrophy

84
Q

Lorenzos Oil can be used to treat ____

A

adrenoleukodystrophy

85
Q

What is the substrate of ketogenesis

A

Acetyl CoA

86
Q

What are the products of ketogenenis?

A
  1. Acetoacetate
  2. beta hydroxybutyrate
  3. Acetone
87
Q

What is the rate limiting step of ketogenesis?

A

Acetoacetyl CoA + Acetyl CoA to HMG CoA

enzyme: HMG CoA synthase

88
Q

of the 3 ketone bodies, which of them can be used as fuel

A
  1. Acetoacetate

2. Beta hydroxybutyrate

89
Q

Acetoactyl CoA is converted to HMG CoA via what enzyme

A

HMG CoA synthase

90
Q

What enzyme converts HMG CoA to acetoacetate?

A

HMG CoA lyase

91
Q

What converts acetoacetate to 3 hydroxybutyrate?

A

3-hydroxybutyrate dehydrogenase

92
Q

What enzyme is lacking in the liver making it unable to use ketone bodies as fuel

A

Succinyl CoA-acetoacetate-CoA transferase

93
Q

Ketosis in alcoholics is due to the excess NADH which shunts what path?

A

Oxaloacetate to malate

94
Q

What is measured by the sodium nitroprusside reaction?

A
  1. Acetone

2. Acetoacetate

Biochemistry (28 decks)

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