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Biochem block 4 > Cholesterol > Flashcards

Cholesterol Flashcards

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0
Q

What are the four main functions of cholesterol

A

Precursor for bile salts
Component of membranes
Precursor for steroids
Precursor for vitamin d

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1
Q

What are the three ways the liver receives cholesterol

A

Synthesizes it de novo
Diet
HDLs

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2
Q

What are the two key points of the structure of cholesterol

A

Very hydrophobic

Has a steroid nucleus

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3
Q

When does the synthesis of cholesterol occur

A

Well fed state

When cholesterol is low

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4
Q

Where does cholesterol synthesis occur

A

Cytoplasm

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5
Q

What is the 1st step of cholesterol synthesis

A

Formation of HMG CoA from 3 Acetyl CoA

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6
Q

What is the rate limiting step of cholesterol synthesis

A

HMG CoA to mevalonate by HMG CoA reductase

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7
Q

What is the cofactor required for HMG CoA reductase

A

NADPH

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8
Q

How many molecules of mevalonate are required to make one cholesterol

A

6

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9
Q

How many Acetyl CoA are required to make one mevalonate

A

3

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10
Q

True or false: Energy is required in the form of ATP and NADPH to make cholesterol

A

True

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11
Q

At what point in the formation of cholesterol does the molecule need a carrier protein

A

Squalene

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12
Q

Smith-lemli-Optiz syndrome is a defect in what part of the cascade

A

Enzymes involved in the conversion of lanosterol to cholesterol

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13
Q

What are some of the symptoms of smith-lemli-Optiz syndrome

A

Ambiguous genitalia
Limb abnormalities
Mental retardation

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14
Q

What two compounds/complex enhance transcription of the HMG CoA reductase gene

A

SCAP- SREBP complex

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15
Q

What do high sterol levels mean for HMG CoA reductase

A

No more sterols needed
HMG CoA reductase to be ubiquinated
Destroyed by proteaosomes

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16
Q

How do statins work

A

Competes for the active site on the HMG CoA reductase enzyme

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17
Q

How is cholesterol transported in the serum

A

Micelles

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18
Q

What do chylomicrons transport

A

Dietary lipids

19
Q

What do VLDLs transport

A

Newly synthesized lipids

20
Q

What do LDLs transport

A

Transport cholesterol away from the liver

21
Q

What do HDLs transport

A

Cholesterol to the liver

22
Q

LDLs have the highest percentage of _______ of the cholesterol carriers

A

Cholesterol

23
Q

HDLs have the highest percentage of ________ of the cholesterol carriers

A

Protein

24
Q

Chylomicrons have the highest percentage of ________ of the cholesterol carriers

A

Fat

25
Q

Which lipoproteins would you expect to be raised based on a pt recently eating a meal

A

Chylomicrons

VLDLs

26
Q

What is the scaffolding protein used in chylomicron formation

A

Apo B-48

27
Q

What is Apo C-11 needed for in chylomicrons

A

Activate lipoprotein lipase

28
Q

What is Apo E needed for in chylomicrons

A

Ligand that will clear chylomicron remnants from the blood

29
Q

What is the scaffolding protein in forming VLDLs

A

Apo B-100

30
Q

Cells that are low on cholesterol will synthesize what to remove cholesterol from the blood

A

LDL receptors (Apo b-100 )

31
Q

What enzyme converts cholesterol into its storage form

A

ACAT

32
Q

What is the scavenger receptor macrophages use to find damaged LDLs

A

SR-A

33
Q

What are three things that can cause damage to LDLs

A

Oxidative stress
High blood sugar
Chemicals

34
Q

What enzyme allows the HDL particle to take up free cholesterol from peripheral tissues

A

ABCA1

35
Q

What esterifies the free cholesterol from peripheral tissues

A

LCAT

36
Q

What protein allows HDLs to transfer cholesterol to the liver and tissues

A

SR-B1

37
Q

Tangier disease is a defect in what?

A

Genetic defect of ABCA1 protein

Needed in HDL synthesis

38
Q

Type 1 hyperlipoproteinemia is a defect in what

A

Deficiency in Apo c-II

39
Q

What is the defect in familial hypercholesterolemia

A

Defect in LDL receptor (Apo b-100 )

40
Q

What is the defect in type three hyperlipoproteinemia

A

Apo E protein

41
Q

What is the only significant way cholesterol leaves the body

A

Bile

42
Q

Bile is ________ soluble than cholesterol

A

More

43
Q

How do bile acid sequesterants reduce serum cholesterol?

A

Reduce enterohepatic circulation of bile salts
Cholesterol is used to replace what is lost
Serum cholesterol is lowered

44
Q

What is the term for gall stones

A

Cholelithiasis

45
Q

What would cause cholesterol gallstones

A

Too little bile salts

Too much cholesterol

Biochem block 4 (6 decks)

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