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Biochemistry > Cholesterol > Flashcards

Cholesterol Flashcards

1
Q

All of the carbon atoms of cholesterol are derived from which molecule?

A

acetate/isoprene units

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2
Q

What is cholesterol a precursor for?

A

Bile Acids, Steroids, and Vitamin D

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3
Q

Where are fatty acids synthesized?

A

Mitochondria

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4
Q

Where is cholesterol synthesized?

A

Cytosol

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5
Q

Which 3 steps are used in Fatty Acid Oxidation that are also used in Cholesterol synthase?

A

1) 2 Acetyl CoA
- Thiolase cleaves CoA

2) Acetoaceyl CoA
- HMG CoA Synthase brings in acetyl CoA and cleaves CoA

3) 3-Hydroxy-3-methylglutaryl CoA (HMG CoA)

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6
Q

Which enzyme reacts with HMG CoA to start cholesterol synthesis?

A

HMG CoA reductase

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7
Q

Are we trying to make energy or store it during cholesterol synthesis?

A

make

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8
Q

What is the first rate limiting step in cholesterol synthesis?

A

HMG-CoA to Mevalonate

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9
Q

Which enzyme is used in the rate limiting step of cholesterol synthesis?

A

HMG-CoA reductase

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10
Q

Which enzyme is used during cholesterol synthesis that acts like a kinase by transfering a high energy phosphate onto a molecule?

A

mevalonate-5-phosphotransferase

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11
Q

What is formed when a phosphate is added to mevalonate?

A

Phosphomevalonate

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12
Q

How many carbons make up cholesterol?

A

30 carbons long

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13
Q

What is formed when a phosphate is added to phosphomevalonate?

A

5-pyrophosphomevalonate

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14
Q

Which enzyme adds a phosphate onto phosphomevalonate to form 5-pyrophosphomevalonate?

A

pyrophosphomevalonate kinase

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15
Q

Which enzyme is used to remove a carbon off of 5-pyrophosphomevalonate?

A

pyrophosphatemevalonate decarboxylase

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16
Q

How many carbons are on an isoprene unit?

A

activated 5 carbon structure

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17
Q

What is the building block of cholesterol?

A

isoprene units

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18
Q

IPP and DPP are how many carbons long?

A

5 carbons long

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19
Q

how many isoprene units are needed to build cholesterol?

A

6x

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20
Q

What us the isomer of isopentyl pyrophosphate?

A

dimethylallyl pyrophosphate

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21
Q

What molecule is formed by DPP and IPP?

A

Geranyl Pyrophosphate

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22
Q

Which enzyme is used to combine DPP and IPP to form Geranyl Pyrophosphate?

A

Phenyl Transferase

23
Q

How many carbons is Geranyl Pyrophosphate consist of?

A

10 carbons

24
Q

What is formed from the condensing of GPP and an additional IPP?

A

Farnesyl Pyrophosphate?

25
Q

How many carbons is FPP consist of?

A

15

26
Q

Which enzyme adds an additional IPP onto Geranyl Pyrophosphate?

A

Phyenyl transferase

27
Q

Which enzyme adds two farnesyl pyrophosphates together?

A

squalene synthase

28
Q

How many carbons long is squalene?

A

30 carbons long

29
Q

What is the name of the molecule that makes the final form of 30 carbon chain that forms cholesterol?

A

squalene

30
Q

is squalene stable or unstable?

A

unstable because of the multiple double bonds and the fact it is so long

31
Q

How many times do the first 3 steps occur during cholesterol synthesis?

A

2x to make 2-15 carbon chains

32
Q

What is the stable ring version of squalene?

A

lanosterol

33
Q

What is lanosterol converted into by a sequence of reactions that use NADPH?

A

Cholesterol

34
Q

How many NADPH are used to stabilize lanosterol to cholesterol?

A

20x

35
Q

Is increased production of cholesterol a negative or positive feedback for HMG-CoA?

A

negative, inhibits further production of cholesterol

36
Q

Insulin _____ HMG reductase

A

increases

37
Q

Glucagon _____ HMG reductase

A

decreases

38
Q

How does cholesterol make hormones/ what does it convert to?

A

Pregnalone

39
Q

What does progesterone convert to which hormones?

A

Hydroxyprogesterone OR Corticosterone

40
Q

Corticosterone can further convert to which hormone?

A

Aldosterone

41
Q

Hydroxyprogesterone can further convert into what hormone?

A

DHEA

42
Q

DHEA can further convert into which hormone?

A

Androstenedione

43
Q

Androstenedione can further convert into what hormones?

A

Testosterone and esterone

44
Q

Testosterone can further convert into what hormones?

A

Dihydrosterone OR Esradiol

45
Q

Which hormone does estrogen come from?

A

Estradiol

46
Q

Which vitamin is derived from cholesterol?

A

Vitamin D

47
Q

Which organ produces estrogen and progesterone?

A

ovaries

48
Q

Which organ produces aldosterone and cortisol?

A

adrenal cortex

49
Q

which two hormones does the adrenal cortex produce?

A

aldosterone and cortisol

50
Q

which two hormones do the ovaries produce?

A

estrogen and progesterone

51
Q

What hormone do the testes make?

A

testosterone

52
Q

Which organ produces testosterone?

A

testes

53
Q

Which gland secretes lutenizing hormone and follicle-stimulating hormone?

A

anterior lobe of the pituitary gland

54
Q

What hormones does the anterior lobe of the pituitary gland secrete?

A

lutenizing hormone and follicle-stimulating hormone

Biochemistry (11 decks)

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