Quiz 3 Cholesterol Synthesis Flashcards Preview

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Flashcards in Quiz 3 Cholesterol Synthesis Deck (31)
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1

Nearly all tissues can synthesize cholesterol from what?

Acetyl CoA

2

20% of cholesterol synthesis happens where?

In the liver

3

Extrahepatic sites cholesterol can be synthesized?

Intestine, adrenal cortex, reproductive tissues

4

Chylomicron remnants go to where and converted to bile salts?

liver

5

Free cholesterol is an essential component of what?

cell membranes (this regulates the fluidty, gives strength to the membrane)

6

Free cholesterol is precursor to?

bile salts and steroid hormones

7

Type of cholesterol not located in membranes and is MORE hydrophobic?

esterfied cholesterol

8

What are two outcomes of excess cholesterol?

Gallstones and Atherosclerosis (cholesterol deposited at the linings of blood vessels)

9

30% of circulating cholesterol is this form?

Free cholesterol

10

Cholesterol Synthesis occurs where in the cell?

Cytosol

11

Reducing power of cholesterol synthesis?

NADPH

12

What things are required in cholesterol synthesis?

ATP, molecular O2, Acetyl CoA

13

What are the 3 stages of cholesterol synthesis?

Stage 1: 3 Acetyl CoA → HMG-COA
Stage 2: HMG-CoA → Mevalonic Acid (mevalonate) → Squalene
Stage 3: Squalene → Cholesterol

14

What is the rate-limiting, key regulatory step of cholesterol synthesis?

HMG-CoA reductase (remember this occurs in the cytosol)

15

Product of HMG-CoA Reductase?

Mevalonate (mevalonic acid)

16

Is HMG CoA reductase reversible or irreversible?

IRREVERSIBLE

17

As cholesterol concentration increases, what does this do to HMG CoA reductase?

Inhibits it (low cholesterol levels stimulate this enzyme)

18

HMG CoA reductase is active or inactive (inhibited) when phosphorylated by AMP-activated protein kinase?

Inhibited when phosphorylated (stimulated when non-phosphorylated)

19

Competitive inhibitors of HMG CoA reductase which block endogenous synthesis of cholesterol?

Statins

20

What type of bile salts are made in the liver and then secreted into the duodenum?

Primary bile salts

21

Which type of bile salts are made in the intestine?

Secondary bile salts

22

All bile salts end in?

Cholic acid or cholate

23

Difference in polar and non polar bile salts?

Number and position of hydroxyl groups

24

What is the precursor for all steroid hormones?

Pregnenolone

25

Cholesterol synthesis an energy requiring pathway?

YES!! Lots of energy required

26

What are the ingredients again for Cholesterol synthesis?

Acetyl CoA, NADPH. O2, and ATP

27

What is the first unique compound in cholesterol synthesis?

Mevalonate

28

Cholesterol is a precursor for?

Bile Salts and steroid hormones

29

Can cholesterol be degregaded? If not how is it excreted?

No, excreted in bile

30

Glucose, fructose, insulin, thyroxine stimulate or inhibit cholesterol synthesis?

Stimulate

31

Glucagon, epinephrine, and statins inhibit or stimulate cholesterol synthesis?

Inhibit