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Biochemistry II > Cholesterol Synthesis > Flashcards

Cholesterol Synthesis Flashcards

1
Q

Cholesterol is a precursor to:

A

Bile acids, steroid hormones, Vitamin D

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2
Q

What is the naming convention of steroid molecules?

A

End in -ol or -one

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3
Q

Name 3 steroid molecules/hormones

A

Cortisol, testosterone, estradiol

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4
Q

Name 2 disorders caused by excess cholesterol

A

Cardiovascular disease and gall stones

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5
Q

What is the test used to diagnose problems in the gall bladder?

A

Cholecystogram

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6
Q

Blood levels of cholesterol are due to what two sources?

A

50% diet
50% synthesized in body’s cells

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7
Q

List the three locations of DeNovo synthesis of cholesterol

A

Liver, adrenals, gonads

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8
Q

How many total carbons are in the cholesterol molecule?

A

27 carbons

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9
Q

List the steps for cholesterol synthesis in order

A

acetyl CoA -> HMG CoA -> mevalonate -> farnesyl pyrophosphate -> squalene -> lanosterol -> cholesterol

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10
Q

What is the end product of Stage 1?

A

Mevalonate

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11
Q

What are the enzymes used in Stage 1?

A

HMG CoA reductase and HMG CoA synthase

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12
Q

What is the allosteric enzyme in Stage 1? What coenzyme is needed?

A

HMG CoA reductase
NADPH+

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13
Q

What hormone increases cholesterol synthesis?

A

Insulin

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14
Q

Name three things that down-regulate cholesterol synthesis

A

Cholesterol, glucagon, and statin drugs

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15
Q

What is the end product of Stage 2?

A

Farnesyl pyrophosphate

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16
Q

What coenzymes are needed for Stage 2?

A

ATP and Mg2+

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17
Q

The end product of Stage 2, farnesyl pyrophosphate, is an important intermediate in the synthesis of what other molecule?

A

CoQ10 aka ubiquinone

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18
Q

In the absence of CoQ10, what is the dose needed to replete the drug induced nutrient deficiency?

A

100mg

19
Q

What is the end product of Stage 3?

A

Squalene

20
Q

What is squalene capable of being?

A

Capable of being a ring, but it is not

21
Q

What is the enzyme used in Stage 3?

A

Squalene synthase

22
Q

What is the location of the enzyme squalene synthase?

A

Endoplasmic reticulum

23
Q

What are the coenzymes for squalene synthase?

A

NADPH+, Mg2+, Mn2+

24
Q

What is the end product of Stage 4?

A

Lanosterol

25
Q

What is the enzyme for Stage 4?

A

Cyclase

26
Q

What is the coenzyme for Stage 4?

A

NADPH+

27
Q

What is the final product of cholesterol synthesis?

A

Cholesterol

28
Q

What coenzyme is needed for Stage 5?

A

NADPH+

29
Q

Name the 7 factors/lifestyle that increase cholesterol synthesis

A
  1. high blood pressure
  2. smoking
  3. male gender
  4. abdominal obesity
  5. lack of exercise
  6. drinking soft vs hard water
  7. elevated serum free fatty acids
30
Q

What is the largest product that cholesterol is used for?

A

Bile salts/acids

31
Q

What enzyme is required for synthesis of bile acids?

A

7 alpha hydroxylase

32
Q

What are the coenzymes for 7 alpha hydroxylase?

A

NADPH+ and Vitamin C

33
Q

What vitamin can be used in high doses to decrease blood cholesterol levels?

A

Niacin (vitamin B3)

34
Q

What is the name of the hormone that increases the synthesis of bile?

A

Hepatocrinin

35
Q

What causes hepatocrinin to be released?

A

Fat in the duodenum

36
Q

What is the name of the hormone that causes the gall bladder to contract?

A

Cholecystokinin

37
Q

Without fiber, how much bile is reabsorbed into the portal system and resecreted?

A

98%

38
Q

Can cholesterol be digested or metabolized?

A

No, it cannot enter Krebs cycle

39
Q

How much cholesterol is excreted in the feces?

A

1 gram

40
Q

What do bacteria convert cholesterol to in the colon?

A

Coprostanol

41
Q

What color is coprostanol?

A

Blue

42
Q

What is steatorrhea?

A

Foul smelling floating stool

43
Q

Guinea pigs can get atherosclerosis if they are deficient in which Vitamin?

A

Vitamin C

44
Q

Natural dietary advice used to decrease blood LDL levels includes what two things?

A

Vitamin C and bran (especially oat bran)

Biochemistry II (13 decks)

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