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Biochemistry Exam 3 > Lecture 3: Lipoproteins > Flashcards

Lecture 3: Lipoproteins Flashcards

1
Q

What are lipids derived from?

A

fatty acids

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2
Q

Provide examples of lipids

A

fats, oils, waxes, steroid, sterols, hormones

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3
Q

What are lipoproteins?

A

transportation form of hydrophobic substances, such as lipids

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4
Q

What are inside lipoproteins?

A

triacylglycerols and cholesterol esters

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5
Q

What does the outside of lipoproteins consist of?

A

phospholipid heads and cholesterol

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6
Q

As a lipoproteins diameter increases the density _____.

A

decreases

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7
Q

What is the most dense lipoprotein?

A

HDL

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8
Q

What is the least dense lipoprotein?

A

VLDL

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9
Q

What are apoproteins?

A

They are on the surface of lipoproteins and provide structures and function by identifying receptors on cells it is looking to bind to.

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10
Q

What are the functions of apoproteins?

A

1) Solubility and structural integrity
2) Receptor-binding and targeting
3) Enzyme activation
4) Exchange

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11
Q

Which lipoprotein is the apoprotein ApoA-1 unique to?

A

Unique to HDL = structural and enzyme activator

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12
Q

Which lipoproteins is the apoprotein ApoB unique to?

A

Unique to non-HDL particles = structural and ligand for receptor binding

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13
Q

What are the major 5 groups of lipoproteins?

A

Chylomicrons, VLDL, IDL, LDL, HDL

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14
Q

Explain ApoB mRNA editing

A

1) Begin with CAA in the intestines, CAA is converted to UAA (stop codon) via cytidine deaminase editing complex
2) The ApoB48 (48% of ApoB100) mRNA is partially translated due to the stop codon
3) ApoB100 is fully translated in the liver

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15
Q

Which organ is ApoB48 located in and what is its function?

A

Located in the intestine (intestinal cells) and is involved in receptor-mediated chylomicron remnant uptake by the liver.

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16
Q

Which organ is ApoB100 located in and what is its function?

A

Located in the liver and required for VLDL-LDL uptake by liver

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17
Q

What is lipoprotein lipase?

A

enzyme required to hydrolyze chylomicrons and VLDL to free fatty acids (FFA) and 1,2-diacylglycerols (DAG

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18
Q

What is the synthesis location for chylomicrons?

A

small intestines

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19
Q

What is the secretion location for chylomicrons?

A

Lymph nodes to blood vessels

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20
Q

What is primary component of chylomicrons?

A

Triacylglycerols

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21
Q

Which apoprotein is specific to chylomicrons?

A

ApoB48

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22
Q

What is the function of chylomicrons?

A

Deliver TAG to cells

23
Q

What does lecithin-cholesterol acyltransferase do?

A

esterifies cholesterol so that it can be easily transported

24
Q

What does acyl-coenzyme A-cholesterol acyltransferase do?

A

uses acyl-coA to add acyl group to cholesterol in liver

25
Q

What is the synthesis location for VLDL?

A

liver

26
Q

What is the secretion location for VLDL?

A

Bloodstream

27
Q

What is the primary component of VLDL?

A

Triacylglycerols

28
Q

Which apoprotein is specific to VLDL?

A

ApoB100

29
Q

What is the function of VLDL?

A

Deliver TAG to body cells

30
Q

What is the function of HDL?

A

Removes cholesterol from tissue and transports it to the liver = reverse cholesterol transport

31
Q

What does the liver dispose of cholesterol as?

A

Bile acids

32
Q

Which cholesterol is known as “good” cholesterol?

A

HDL

33
Q

What is the synthesis location of LDL?

A
  • In the liver as VLDL
  • Uses lipoprotein lipase to release all free fatty acids - Converts cholesterol esters using LCAT (lecithin cholesterol acetyltransferase)
34
Q

What is the secretion location for LDL?

A

Bloodstream

35
Q

What is the primary component of LDL?

A

Cholesterol

36
Q

Which apoprotein is specific to LDL?

A

There isn’t one

37
Q

What is the function of LDL?

A

Delivers cholesterol to body cells

38
Q

What does cholesterol ester transfer protein do?

A

Transfers HDL to VLDL for uptake by the liver

39
Q

What is the synthesis location for HDL?

A

liver and intestines

40
Q

What is the secretion location for HDL?

A

Bloodstream

41
Q

What is the primary component of HDL?

A

Cholesterol

42
Q

Which apoprotein is specific to HDL?

A

Apo-A1

43
Q

Explain what HMG CoA reductase, ACAT, and LDL receptors do when cholesterol is low

A

1) HMG CoA reductase decreases because more cholesterol does not need to be made due to receiving it from a diet
2) ACAT increases because the cholesterol that was absorbed needs to be stored
3) LDL receptors decrease because more cholesterol does not need to uptake

44
Q

What causes familial hypercholesterolemia?

A

Mutation in LDL receptor gene
The liver does not recognize that the body has too much cholesterol = HMG CoA reductase is not downregulated = cholesterol continues to be synthesized

45
Q

What are the metabolic characteristics of familial hypercholesterolemia?

A

High LDL and plasma cholesterol levels

46
Q

What are the physical characteristics of familial hypercholesterolemia?

A

Orange-yellow xanthomas

47
Q

Where are sources of cholesterol found?

A

Only in animal food products (meat, eggs, dairy, etc). Not in fruits, vegetables, or nuts.

48
Q

Which organ synthesizes cholesterol?

A

Liver

49
Q

What is atherosclerosis?

A

It is plaque formation within endothelial lining of arteries causing blockages in blood flow

50
Q

What is the LDL hypothesis?

A

1) Elevated levels of LDL cholesterol and apoB100 directly contribute to atherosclerosis
2) Oxygen radicals in the endothelial lining of the arteries oxidize LDL and retain them
3) Activated endothelial cells become inflamed = recruit macrophages
4) Macrophages take up LDL and are saturated with cholesterol = forming foamy cells in the endothelium
Hemorrhage/tissue damage from plaque microvessels

51
Q

What is a normal total cholesterol fasting blood level?

A

< 200 mg/dl

52
Q

What is a normal LDL cholesterol fasting blood level?

A

< 100 mg/dl

53
Q

What is a normal HDL cholesterol fasting blood level?

A

≥ 60 mg/dl

54
Q

What is a normal triglyceride fasting blood level?

A

< 150 mg/dl

Biochemistry Exam 3 (4 decks)

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