Lipids and Lipoproteins

Question 1

what are the 3 major sources of triacyglycerol?

Answer 1

dietary = processed in intestinal cells

de novo TAG in hepatocytes and adipocytes

Question 2

What does HDL give to VLDL, IDL, and LDL?

Answer 2

cholesterol esters

Question 3

What is the composition of chylomicrons like relative to HDL?

Answer 3

chylomicrons = mostly TAGs, least protein
HDL = least TAGs, most protein

Question 4

What is the function of lipoproteins?

Answer 4

serve as vehicles for transport of cholesterol, cholesterol esters, TAGs, and fat soluble vitamins

Question 5

What is a xanthoma?

Answer 5

irregular yellow patch or nodule on skin caused by deposition of lipids
seen in type I and II hyperlipoproteinemia

Question 6

What are the 5 different types of lipoproteins?

Answer 6

chylomicrons
VLDL
IDL
LDL
HDL

Question 7

What does HDL exchange with chylomicron?

Answer 7

ApoC-II and ApoE

Question 8

How is the uptake of LDL accomplished?

Answer 8

receptor-mediated endocytosis –> clathrin coated pit –> vesicle –> endosome –> lysosome –> cholesterol and amino acids used
*LDL receptor gets recycled and put back on the cell surface

Question 9

What apolipoproteins are on HDL?

Answer 9

ApoA-I
ApoC-II
ApoE

Question 10

What apolipoprotein is on LDL?

Answer 10

ApoB-100

Question 11

What is the function of ApoB-100?

Answer 11

facilitates transport of everything VLDL, IDL, and LDL; made in the liver

Question 12

What is the function of ApoB-48?

Answer 12

facilitates transport

Question 13

What apoliproteins are on VLDL?

Answer 13

apoB-100
apoC-II
ApoE

Question 14

How many calories are stored in the body in protein?

Answer 14

24000 = muscle

Question 15

What is the function of ApoC-II?

Answer 15

activates lipoprotein lipase

Question 16

Rank the 5 types of lipoproteins by size, largest to smallest.

Answer 16

chylomicrons
VLDL
IDL
LDL
HDL

Question 17

How many calories are stored in the body in TAGs?

Answer 17

100,000 = fat and muscle

Question 18

What is the function of ApoE?

Answer 18

facilitates uptake into liver

Question 19

What is is type II hyperlipoproteinemia?

Answer 19

aka familial hypercholesterolemia
defect in LDL receptor that recognizes ApoB100 –> can’t uptake into cells
heterozygous = cholesterol 300-500
homozygous = >800

Question 20

What are the main beneficial roles of HDL?

Answer 20

scavenges and removes LDL from periphery and takes it to the liver to be recycled and processed
antioxidant and anti-inflammatory properties
keeps endothelium of vessels healthy

Question 21

What do VLDL, IDL, and LDL all give to HDL?

Answer 21

CETP = cholesterol ester transfer protein
Triacylglycerols = TG
Phospholipids = PL

Question 22

What does HDL exchange both ways w/ VLDL?

Answer 22

Apo C-II, ApoE

Question 23

What is type I hyperlipoproteinemia?

Answer 23

inability to hydrolyze TAGs in chylomicrons and VLDLS
either deficiency in LPL or apoC-II
LPL deficiency is worse - see in infancy
Plasma TAG levels >1000

Question 24

What apolipoproteins are on IDL?

Answer 24

ApoB-100

ApoE

Question 25

How many calories are stored in the body in glycogen?

Answer 25

600 kCal = liver and muscle

Question 26

What is the structure of lipoproteins?

Answer 26

outer shell = monolayer of phospholipids, cholesterol, and apolipoproteins
inner core: hydrophobic TAGs, cholesterol esters

Question 27

How many calories are stored in the body in glucuse?

Answer 27

40 kCal = blood

Question 28

What apolipoproteins are on chylomicrons?

Answer 28

ApoB-48
ApoC-II
ApoE

Question 29

How do you treat type II hyperlipoproteinemia?

Answer 29

heterozygous ppl respond to diet, statins and bile acid binding resins
homozygous need LDL apheresis and liver transplantation