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EOM 1 - Test 4 > Hardman - Cholesterol > Flashcards

Hardman - Cholesterol Flashcards

1
Q

Isoprenes

A

Consist of terpenes and steroid

Plant pigments and odors

5-Carbon initiator Unit in Synthesis of Cholesterol

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2
Q

Prenylation

A

Attachment of farnesyl or geranylgeranyl group

Act as anchor to membranes

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3
Q

What two molecules begin synthesis of ketons and cholesterol?

Where does this occur?

A

Acetoacetyl CoA + Acetyl CoA

=

HMG-CoA

Cytoplasm

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4
Q

What is the commited step in cholesterol formation?

A

Synthesis of mevalonate

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5
Q

What is the rate limiting enzyme in cholesterol formation?

A

HMG-CoA Reductase

(catlyzes HMG-CoA to Mevalonate)

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6
Q

What is mevalonate converted to?

A

5-carbon IPP (isopentenyl pyrophosphate)

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7
Q

What is IPP isomerized to?

How many ATP does this require?

A

IPP isomerized to dimethylallyl pyrophosphate

Requires 3 ATP

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8
Q

How many molecules of IPP are required to form squalene?

What are the intermediates during multiple condensations?

What is total ATP required?

A

Six IPP’s are condensed to form squalene

Dimethylallyl

I

Geranyl

I

Farnesyl

I

Squalene

18 ATP Total

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9
Q

Start to finish: Cholesterol Synthesis

A

Acetoacetyl CoA+Acetyl CoA

I

HMG-CoA

***I (HMG-CoA Reductase)***

Mevalonate

I

5-P Mevalonate

I

IPP

I

Dimethylallyl

I

Geranyl

I

Farnesyl

I

Squalene

I

Lanosterol

I

Cholesterol

Ah! Ah! Help Me Plan In Diet Good Food Stay Low in Cholesterol

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10
Q
A
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11
Q

How is cholesterol synthesis regulated?

A

HMG-CoA Reductase rate limiting enzyme

Four methods:

  1. Sterol Dependent
    • (excess cholesterol binds SCAP, blocks release of SREBP)
  2. Sterol Independent
    • Phosphorylated HMG CoA Reductase
  3. Hormonal
    • Activate: Insulin
    • Inhibit: Glucagon/Epinephrine
  4. Inhibition by Drugs
    • Statins (w/side effects)
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12
Q

What are the major plasma lipoproteins from least dense to most dense?

A

Least: Chlyomicron

VLDL

IDL

LDL

Most: HDL

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13
Q

Chylomicron

A

Largest lipoprotein

Dietary fat transport

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14
Q

VLDL

A

Endogeneous fat transport

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15
Q

IDL

A

LDL precursor

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16
Q

LDL

A

Cholesterol transport

17
Q

HDL

A

Reverse cholesterol transport

18
Q

How do the intestines and liver package cholesterol (and fats) to enter the capillaries?

How do extra hepatic tissues transport cholesterol to the liver?

A

Intestines: Chylomicrons

Liver: VLDL

Extrahepatic: HDL

19
Q

What apolipoprotein is unique to chyolomicrons?

Where are enzymes for chylomicrons located?

What adds apo E and apo C

A

B-48

Smooth ER

Circulating HDL

20
Q

What enzyme hydrolyses TAG to FAs + Glycerol?

What activates?

What removes chylomicron remnants?

A

Lipoprotein Lipase

Activate: Insulin

Liver clears remnants

21
Q

What lipoproteins have the most TAG content?

A

Chylomicron highest TAG % (least dense)

HDL have lowest TAG % (most dense)

22
Q

What apolipoproteins tag VLDL?

A

B-100

C-11

23
Q

What happens to apolipoprotein lipase C and E following degradation?

A

Returned to HDL

24
Q

What is tag is recognized for uptake of IDL and LDL?

How many isoforms are there?

What are results of defects in each?

A

apo E

E2, E3, E4

E3: Familial Hyperlipoproteinemia (high cholesterol), early athersclerosis

E2: Reduce Alzheimers

E4: Increase Alzheimers

25
Q

Degradation of Cholesterol: Sterol Nucleus

A

Converted to bile acids

26
Q

Degradation of Cholesterol: Cholesterol

A

Secreted into gall bladder

27
Q

Degradation of Cholesterol: Futher uses?

A

Synthesis of sterol hormones

28
Q

What can excess cholesterol lead to in the gall bladder?

A

gall stones

29
Q

Excess cholesterol forms what?

A

Bile acids, bile salts

30
Q

What is the rate limiting step of steroid synthesis?

A

Conversion of cholesterol to pregnenolone

31
Q

What is the order of steroid synthesis?

A

Cholesterol

I

Pregnenolone

I

Progrestagens

I

  1. Glucocroticoids
  2. Mineralcorticoids
  3. Androgens
32
Q

What are androgens converted to?

A

Testosterone and Estradiol

33
Q

What are estrogens and testosterone vital for?

A

Reproduction and physical development

34
Q

What are progestins vital for?

A

Maintenance of pregnancy

35
Q

What are two sources of Vitamin D?

What occurs during deficiency?

A

Sunlight and Supplementation

Children: Ricketts

Adults: Osteoperosis

36
Q

How does thermogenesis in BAT occur?

A

Low T activates cascade for thermogenin and UCP-1 to uncouple ETC, releasing heat

37
Q

What is the rate limiting step of steroid formation?

A

Cholesterol (C27) to Pregnenolone (C21)

38
Q

Vitamin D is converted to its active form where?

A

Kidney (Vit D to Calcitriol)

39
Q
A

EOM 1 - Test 4 (19 decks)

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