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Dr. Erb > 19b > Flashcards

19b Flashcards

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1
Q

What are the 4 steps of cholesterol synthesis?

A
  1. 3 acetate —> mevalonate
  2. mevalonate —> phosphorylated 5-c isoprene
  3. 6 isoprenes polymerize to form 30-c linear squalene
  4. Squalene cyclizes to form 4 rings to produce —> cholesterol
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2
Q

What enzymes are used from acetyl coa —>mevalonate?

A

thiolase

hmg coa reductase

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3
Q

What enzymes are used from mevalonate —>

A

mevalonate 5-phosphotransferase
phosphomevalonate kinase
pyrophospho - mevalonate decarboxylase

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4
Q

__ adds 1 oxygen to the end of the squalene chain.

substrate formed?

A

Squalene Monooxygenase

Squalene 2,3 epoxide

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5
Q

At which point do animal and plant cholesterol synthesis pathways converge?

A

Formation of Squalene 2,3 epoxide when 1 oxygen is added to the end of squalene.

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6
Q

What is the cyclization produce in animals that converts to cholesterol?

A

Lanosterol

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7
Q

What is the cyclized product in animals and plants of cholesterol?

A

Fungi —–> Ergosterol

Plants —-> Stigmasterol

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8
Q

In plants, what is the final product of cholesterol synthesis?

A

Stigmasterol

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9
Q

In fungi, what is the final product of cholesterol synthesis?

A

Ergosterol

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10
Q

How many ATP are used to make 1 cholesterol?

A

18

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11
Q

Where does Cholesterol go after synthesis?

A

Exported as bile acids, biliary cholesterol or cholesterol esters.

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12
Q

In vertebrates, most cholesterol are made in the

A

liver

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13
Q

Other tissues convert cholesterol into

A

Steroid Hormones

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14
Q

True or False

Bile Acids assist in emulsification of fats

A

True

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15
Q

Bile is

stored in
secreted in

A

Gallbladder

Small Intestine

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16
Q

How do bile acids emulsify fats?

A

Surround droplets of fats, increase surface area for attach by lipases

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17
Q

Tissues convert cholesterol into

A

steroid hormones

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18
Q

True or False

Cholesteryl esters are more polar than cholesterol.

A

False; nonpolar

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19
Q

What make cholesterol more hydrophobic and enter to membranes?

A

Cholesterols have a fatty acid that is esterfied to an oxygen

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20
Q

How are cholesterols carried on lipoprotein particles?

A

Plasma and spherical particles

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21
Q

What is the surface made up of a lipoprotein made up of?

A

apolipoprotein & phospholipid monolayer

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22
Q

What is the interior of a lipoprotein made up of?

A

TAG’s, cholesteryl esters, and cholesterol

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23
Q

The inside of the lipoprotein is and outside is?

Study These Flashcards
A

Inside —> hydrophobic

Outside —> hydrophilic

24
Q

Cholesterol is transported in _______ to other tissues stored in the liver.

25
What are the 4 major classes of lipoprotein particles?
Chylomicrons VLDL LDL HDL
26
What are the smallest major class of lipoprotein particles?
HDL; and most dense
27
What is the largest major class of lipoprotein particles?
Chylomicrons; least dense
28
What does the apolipoprotein mean?
Protein part of a lipoprotein particle
29
Provides sites for the particle to bind to the cell surface receptors, activate enzymes
Apolipoproteins
30
At least 10 have been identified
Apolipoproteins
31
____ transport endogenous lipids
VLDL
32
Cholesteryl esters and TAG's from excess FA and cholesterol are packed into
VLDL
33
Excess carb in the diet can also be made into TAG in the __ and packed into.
Liver VLDL
34
What is the primary function VLDL?
Release TAG into FFA into bloodstream
35
VLDL take TAGS to which two?
Adipose Tissue | Muscle
36
-Activates-II activated lipoprotein lipase to release FFA
ApoC-II
37
Take up the FFA, reconvert them to TAGs, and store them to lipid droplets.
Adipocytes
38
-uses the TAG for energy
Muscle
39
____ remnants become LDL
VLDL
40
LDL is delivered to
Adrenal Gland Gonads Muscle Adipose Tissue
41
Removal of TAG from VLDL produces
LDL
42
Because TAG is removed, ___is enriched in cholesterol/cholesteryl esters.
LDL
43
What is the major apolipoprotein?
ApoB-100
44
___ carry cholesterol from the liver to the muscle and adipose tissue.
LDL
45
Muscle and adipose tissue have ___ receptors that recognize apoB-100
LDL
46
ApoB-100 enables myocytes and adipocytes to take up cholesterol via ___-
receptor-mediated endocytosis
47
How do plaques form?
1. monocyte is attracted to oxidized lipoproteins that cluster and stick to ECM 2. Monocyte differentiation into macrophages 3. Foam Cells (macrophages) ingest lipoproteins 4. Free cholesterol accumulates in membranes and droplets. 5. Cholesterol rich plaque forms
48
How do statin drugs work?
They bind to HMG CoA Reductase, lower the cholesterols because it blocks the synthesis of cholesterols. It looks like mevalonate and is a competitive inhibitor
49
True or False; Do statins stabilize plaques by removing cholesterol from them?
Yes
50
What is the 1st statin?
Lovastatin
51
True or False; Statin Drugs helps alleviate the effects of LDL
True (reverses the activity of LDL)
52
___ picks up cholesterol from nonliver tissues, including foam cells at growing plaques.
HDL
53
____Carries cholesterol back to the liver
HDL
54
What is Tangier disease?
ABCA1 defect; familial HDL deficiency
55
Which cholesterol is cardioprotective?
HDL
56
Steroid Synthesis takes place in the
mitochondria
57
True or False | Steriod Synthesis uses mixed-function oxidases, NADPH and Cytochrome-P50
True

Dr. Erb (8 decks)

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