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Biochemistry > Cholesterol > Flashcards

Cholesterol Flashcards

1
Q

Draw the steroid nucleus

A

ABCD rings

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2
Q

The hydroxyl group in the cholesterol is located in what ring?

A

Ring A

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3
Q

The hydrocarbon tail is located in the what ring

A

Ring D

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4
Q

How many carbons are there in a cholesterol?

A

27 carbons

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5
Q

The double bond of cholesterol happens in what carbons

A

C5-C6

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6
Q

What are the derivatives of cholesterol?

A
  1. Bile acids
  2. Adrenal hormones
  3. Sex hormones
  4. Vitamin D
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7
Q

What are the enzymes involved in converting cholestero to 7alpha hydroxycholesterol used in bile acid synthesis?

A

7alpha hydroxylase

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8
Q

What are your primary bile acids?

A
  1. Cholic acid

2. Chenodeoxycholic acid

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9
Q

What are your secondary bile acids

A
  1. Deoxycholic acid

2. Lithocholic acid

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10
Q

What are your bile sats?

A
  1. Conjugated taurine and glycine
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11
Q

What is the substrate for cholesterol synthesis?

A
  1. Acetyl Coa
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12
Q

Which part of the cell does cholesterol synthesis occur?

A
  1. Cytosol

2. Endoplasmic reticulum

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13
Q

What is the rate limiting step in cholesterol synthesis?

A
  1. HMG CoA to Mevalonate via HMG CoA reductase
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14
Q

What enzyme converts acetyl CoA + Acetoacetyl CoA to HMG CoA

A

HMG CoA synthase

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15
Q

HMG CoA is converted to mevalonate via this enzyme

A

HMG-CoA reductase

Needs 2 NADPH

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16
Q

Mevalonate is converted to what intermediate in cholesterolm synthesis??

A

Isopentenyl pyrophosphate C5

C10 = geranyl pyrophosphate

C15 = farnesyl pyrophosphate

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17
Q

Squalene is formed from combining what intermediate?

A

Farnesyl pyrophosphate (C15)

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18
Q

What enzyme creates lanosterol from squalene?

A

cyclase

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19
Q

What is the immediate precursol of cholesterol?

A

Lanosterol

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20
Q

Product inhibition of cholesterol synthesis is possible due to what transcription factor?

A

Sterol regulatory element binding protein (SREBP)

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21
Q

In cholesterol synthesis, a dephosphorylated enzyme is ___ (active/inactive)

A

active

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22
Q

What hormones increases HMG-CoA reductase?

A
  1. Insulin

2. Thyroid hormone

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23
Q

What hormones decreases HMG-CoA reductase?

A
  1. Glucagon

2. Glucocorticoids

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24
Q

Which part of the cholesterol structure that cant be metabolized by humans?

A

cholesterol ring

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25
Q

Bacteria in the intestines convert cholesterol to what compounds?

A
  1. Coprostanol

2. Cholestanol

26
Q

[diagnose]

deficiency in 7-dehydrocholesterio reductase

A

Smith-Lemli-Opitz Syndrome

27
Q

[diagnose]

low plasma cholestero and elevated 7-dehydrocholesterol

dysmorphic facial features, microcephaly, mental retardation, congenital heart disease, malformations, still born

A

Smith-Lemli-Opitz syndrome

28
Q

What is the most common enzyme deficiency in congenital adrenal hyperplasia

A

21-apha hydroxylase deficiency

29
Q

[Diagnosis]

Overproduction of androgen, musculinization of external genitalia in females and early virilization in males

A

21-alpha hydroxylase deficiency

30
Q

[Diagnosis]

what enzyme is deficient when patient has a decreased serum cortisol, aldosterone, corticosterone

A

11-beta1-hydroxylase deficiency

31
Q

[Diagnosis]

“low renin” hypertension

A

11 beta 1 hydroxylase deficiency

32
Q

[Diagnosis]

___ autoimmune destruction of adrenal cortex

A

addison disease

Addison = adrenal destruction

33
Q

[Lipid transport]

The core of plasma lipoprotein is made of what type of lipids?

A

neutral lipids

34
Q

[Lipid transport]

Example of peripheral apoprotein

A

Apo C

35
Q

[Lipid transport]

example of integral apoprotein

A

Apo B

36
Q

[Lipoprotein]

largest diameter, lowest density, highest TAG

A

chylomicron

37
Q

[Lipoprotein]

highest cholesterol content

A

LDL

38
Q

[Lipoprotein]

highest protein content

A

HDL

Density increases as you lower lipid content

39
Q

[Apoprotein]

Found mainly in HDL

A

Apo A-1

structural component of HDL

40
Q

[Apoprotein]

co-factor of lecithin:cholesterol acyl transferase

A

Apo A-1

41
Q

[Apoprotein]

mediates assembly and secretion of VLDL

A

ApoB 100

42
Q

[Apoprotein]

structural protein of VLDL, IDL, LDL

A

ApoB 100

43
Q

[Apoprotein]

mediates secretion fo chylomicrons from small intestines

A

Apo B-48

44
Q

[Apoprotein]

co factor of lipoprotein lipase

A

Apo C-II

45
Q

[Apoprotein]

mediates uptake of chylomicron remnants and IDLs

A

Apo E

46
Q

[Hyperlipoproteinemia]

high TAG, low LDL, Low HDL

Xanthomas, recurrent pancreatitis, hepatosplenomegaly,

NO INCREASED RISK OF CAD

A

Type I - Familial lipoprotein lipase deficiency

due to deficient lipoprotein lipase OR apo CII

47
Q

[Hyperlipoproteinemia]

High LDL, high cholesterol

A

Type IIa - hypercholesteriolemia

Defective LDL receptor

48
Q

[Hyperlipoproteinemia]

Hypercholesterolemia
Xanthomas
Atherosclerosis
defective Apo E

A

Type III

familial dysbetalipoproteinemia

49
Q

[Hyperlipoproteinemia]

High TAG, high VLDL
Subnormal LDL subnormal HDL

Associated with coronary disease, type 2 DM, obesity, alcoholism

A

Type IV

Familial hypertriacylglycerolemia

due to overproduction of VLDL

50
Q

[Hyperlipoproteinemia]

Thrombosis due to inhibition of fibrinolysis

A

Familial lipoprotein A excess

elevated LpA

51
Q

What lipoprotein which is nearly identical to LDL?

A

lipoprotein A

52
Q

[Hyperlipoproteinemia]

high HDL

A

Familial hyperalphaproteinemia

53
Q

[Hypolipoproteinemia]

low TAG, accumulation of TAG in liver and intestine

can be treated using large doses of fat soluble vitamins (vitamin E)

A

Abetalipoproteinemia - defect in loading of Apo B with lipid

54
Q

[Hypolipoproteinemia]

high TAG due to absence of Apo CII leading to inactive LPL; atherosclerosis in elderly

A

Familial alpha-lipoprotein deficiency

low or near absence of HDL

55
Q

[Chylomicron]

From the intestine to the capillaries

A
  1. Nascent chylomicron (Apo B48)
  2. HDL is added (Apo CII, Apo E)
  3. Chylomicron in capillaries (Apo B 48, Apo C-II, Apo E)
56
Q

[Chylomicron]

from the capillaries to the liver

A
  1. TAG removed from chylomicron by lipoprotein lipase (activated by Apo CII)
  2. Apo CII returned to HDL
  3. Chylomicron remnant goes to the liver (Apo E, Apo B 48)
  4. Apo E binds to receptor in liver
57
Q

[VLDL]

from liver to capillaries

A
  1. Nascent VLDL (Apo B 100)
  2. HDL is added (Apo CII, Apo E)
  3. VLDL in capillaries (Apo B100, Apo C-II, ApoE)
58
Q

[VLDL]

From capillaries to extrahepatic tissue liver

A
  1. VLDL (Apo B100, Apo E, Apo C-II)
  2. Lipoprotein lipase degrades TAG (activated by Apo CII)
  3. Apo CII and APO E are returned to HDL
  4. Apo B-100 binds to extrahepatic tisse and liver
59
Q

[HDL]

what is enzyme assimilates cholesterol in VLDL to be used by HDL?

A

CETP

60
Q

[HDL]

What enzyme releases cholesterol esters in the liver?

A

ACAT

61
Q

[HDL]

What enzyme releases cholesterol esters from the cell?

A

LCAT

Biochemistry (28 decks)

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