2.7 Cholesterol Synthesis Flashcards Preview

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Flashcards in 2.7 Cholesterol Synthesis Deck (22):
0

All three reactions of the first step in cholesterol synthesis

Acetyl CoA --> Acetoacetyl CoA
Acetoacetyl CoA --> HMG CoA
HMG CoA --> Mevalonate

1

Enzyme of first step of cholesterol synthesis

HMG CoA Reductase

(KEY REGULATORY ENZYME)

2

2nd step in cholesterol synthesis

Mevalonate --> Formation of Isoprenoids

3

The two versions of isoprenoids

Isopentenyl Pyrophosphate
Dimethylallyl Pyrophosphate

4

Isoprenoids are the building blocks for what important molecule in electron transport chain

Ubiquinone

5

Outline third step of cholesterol synthesis

Condensation of Isoprene into Squalene (30 carbon molecule).
(5+5=10 --> 10+5=15 --> 15+15=30)

6

What occurs in the fourth step of Cholesterol Synthesis

Cyclization of Squalene to Lanosterol

7

What is the rate limiting step of Cholesterol Synthesis Pathway

HMG-CoA to Mevalonic Acid

8

What are the two paths of the intermediate HMG-CoA

1. Cytosolic Pathway - HMG-CoA is used to make cholesterol
2. Mitochondrial Pathway - HMG-CoA is used to make Ketone Bodies

9

What enzyme catalyzes reaction of HMG CoA to Ketone BOdies

HMG-CoA Lyase

10

How is Cholesterol Synthesis regulated during High Cholesterol levels

SCAP sequesters SREBP in ER

11

How is Cholesterol Synthesis regulated in Low Levels of Cholesterol

SCAP and SREBP are moved to Golgi.
In Golgi, SCAP is released and SREBP is clipped and made small to go to nucleus. It then turns on SRE to transcribe HMG CoA-Reductase

12

What is the common intermediate for all 5 classes of steroids

Pregnolone

13

Name the 5 classes of steroids

Androgens, Estrogens, Progestagens, Glucocorticoids, Mineralocorticoids

14

How to synthesize phospholipids

Take phosphate group off of phosphatidate and add CDP. Then the head group can e added to form whatever form of Phospholipid

15

T or F, Phospholipids cannot be interconverted

False. They can be interconverted

16

What type of messenger molecules are eicosanoids?

Paracrine and Autocrine

17

Name the three different classes of eicosanoids

Leukotriene
Thromboxanes
Prostaglandins

18

What enzyme catalyzes Arachidonic Acid to Leukotrienes?

Lipoxygenase

19

What enzyme catalyzes Arichidonic Acid to Prostaglandin

Cyclooxygenase

20

Omega 3 eicosanoids from from where and have what function?

From EPA
Anti-Inflammatory

21

What is the key enzyme in the synthesis of prostaglandins and thromboxanes

Cyclooxygenase