Quiz 3: Lipids and Lipoproteins

Question 1

Triglyceride Transport (Exogenous Transport)

Answer 1

Via chylomicrons and VLDL
Dietary lipids absorbed and assembled with ApoB-48 into chylomicrons which are broken down in circulation to triglyceride and chylomicron remnants for metabolism or recycling through the liver.
Lipoprotein lipase frees Free fatty acids and glycerol from Triglycerides

Question 2

Triglyceride Metabolism

Answer 2

Release of Fatty Acids from cells for energy, recycling of glycerols into triglycerides
Lipase, lipoprotein lipase, epinephrine and cortisol break down triglycerides

Question 3

Cholesterol Forms

Answer 3

Unsaturated steroid alcohol when esterified: fatty acid attached with ester bond
Free form is unsterified

Question 4

Cholesterol Precursors

Answer 4

Bile acids, steroid hormones, and Vit D

Question 5

Cholesterol Transport

Answer 5

LDL is primary carrier

Question 6

Lipoprotein (Definition)

Answer 6

Molecules that combine insoluble dietary lipids with water soluble proteins for transport; micelles are spherical with an inner core of neutral fat

Question 7

Chylomicrons (Definition)

Answer 7

Largest lipoprotein with lowest density, form in intestines to transport triglycerides; normally enter circulation and are metabolized then taken to the liver to be further modified
They are 86% Triglyceride

Question 8

VLDL

Answer 8

Carries triglycerides synthesized in liver (endogenous transport); normally secreted into blood from liver (after being packaged in VLDL) to be metabolized in peripheral tissues into triglycerides and VLDL remnants or intermediate density lipoproteins for use in metabolism or recycling through the liver
Apo B is the major protein

Question 9

IDL

Answer 9

intermediate-density-lipoprotein

Transitional form between VLDL and LDL, they carry endogenous triglycerides and cholesterol esters

Question 10

LDL

Answer 10

Major cholesterol carrier, largely endogenous cholesterol
Easily taken up by cells, and are thus assoc. with athlerosclerosis
Normally brings cholesterol to peripheral cells for membrane synthesis and hormone creation –> Infiltrate into extracellular space of vessel wall and cleared by macrophages (Macrophages with too much lipid may turn into foam cells which may be plaque precursors)
Apo B is the major protein

Question 11

HDL

Answer 11

Made in the liver and intestine of recycled chylomicron and VLDL molecules; normally removes excess cholesterol from peripheral tissues (antiatherogenic effect)
Apo A-1 is the major protein

Question 12

Lp(a)

Answer 12

Mostly cholesterol esters, phospholipids, and apolpoprotein (a)
Elevated levels are assoc. with coronary heart disease, heart attack, and cerebrovascular disease

Question 13

Cholesterol Ranges

Answer 13

Total: < 200, high: >240
HDL: > 60, at risk for heart disease: < 40
LDL: < 100, High: 160-189

Question 14

Lipid soluble Vitamins

Answer 14

A,D,E, and K

Question 15

Time needed to utilize different energy sources

Answer 15

Glucose - minutes
Glycogen- 1 day
Protein - 10 day
Lipids - 30-40 days with water

Question 16

Functions of cholesterol

Answer 16

Precursor of steroid hormones
Cell membrane component
Precursor of bile salts

Question 17

Apolipoprotein

Answer 17

The protein portion of the transport molecule, free of the lipid component
Apolipoprotein A: major portion of HDL
Apolipoprotein B: major portion of LDL
Apolipoprotein C: major protein of VLDL and Chylomicrons
large: apoB (B-48 and B-100): atherogenic
smaller: apoA-I, apoC-II, apoE

Question 18

Cholesteryl ester

Answer 18

A compound of cholesterol and a fatty acid

Question 19

Plasma Lipid Components

Answer 19

Cholesterol, Trigylcerides, Phospholipids, and non-esterified fatty acids

Question 20

Normal proportions of lipoproteins

Answer 20

LDL: 60-70%
HDL: 20-35%
VLDL: 5-12% (Very Low Density Lipoproteins)

Question 21

Triglycerides Function

Answer 21

Primary form of lipid storage

Question 22

Cholesterol Function

Answer 22

Important in cellular physiology, a precursor to Steroid hormones
LDL takes it to cells, HDL takes it out of cells

Question 23

Chylomicrons Function

Answer 23

Dietary (exogenous) triglycerides

Question 24

VLDL Function

Answer 24

Endogenous triglycerides

Question 25

LDL Function

Answer 25

Cholesterol to cells

Question 26

HDL Function

Answer 26

Cholesterol out of cells

Question 27

Triglyceride Testing Methods

Answer 27

Enzymes are the best method, usually involving freeing glycerol by lipase

Question 28

HDLc

Answer 28

Direct/Homogeneous assays measure without pretreatment

Indirect methods remove chylomicrons, VLDL, and LDL through precipitation

Question 29

LDLc

Answer 29

Direct/Homogeneous assays measure without pretreatment

Question 30

Friedewald Method

Answer 30

Calculation of LDLc and VLDLc when Triglycerides are

Question 31

Triglyceride Structure

Answer 31

One glycerol with 3 fatty acids attached via ester bonds, 95% of all fats in adipose tissue are trigycerides