Lecture 9- Lipid Transport

Question 1

why do fats need to be packaged and kept soluble

Answer 1

so they can be transported in the blood

Question 2

what is the role of O-acyltransferase enzymes

Answer 2

transferring an acyl (fatty) acid group

Question 3

what form is cholesterol most commonly found in

Answer 3

most commonly found in the form of cholesterol ester which is when there is a fatty acid attached

Question 4

what will inhibit the cholesterol synthesis pathway

Answer 4

if there is a lot of cholesterol coming from the diet

Question 5

what enzyme is inhibited to inhibit the cholesterol synthesis pathway

Answer 5

HMG CoA reductase

Question 6

what does HMG CoA reductase do and why is this important

Answer 6

converts HMG CoA to mevalonate = rate limiting step of cholesterol synthesis pathway

Question 7

where is cholesterol found

Answer 7

in the plasma membrane

Question 8

what does cholesterol control in the plasma membrane

Answer 8

the fluidity of the membrane

Question 9

what is the dietary source for cholesterol

Answer 9

animal products

Question 10

what is cholesterol the precursor for

Answer 10

steroid hormones, bile acids and vitamin D

Question 11

what is cholesterol a major constituent of

Answer 11

lipoproteins

Question 12

what is cholesterol important for the transport of

Answer 12

fat soluble vitamins

Question 13

how is cholesterol important for neuronal function

Answer 13

its a part of the myelin sheath

Question 14

what is in the middle of the plasma lipoprotein structure

what is on the outside

Answer 14

esterfied cholesterol and triglyceride

Phospholipids and Unesterfied cholesterol

Question 15

what are the 4 main classes of lipoproteins

Answer 15

chylomicrons
very low density lipoprotein
low density lipoprotein
high density lipoprotein

Question 16

what is a characteristic of chylomicrons and VLDL

Answer 16

triglyceride rich

Question 17

what is a characteristic of very LDL and HDL

Answer 17

Cholesterol rich

Question 18

what is a characteristic of high density lipoprotein

Answer 18

densest because of the high protein content

Question 19

what do ApoB48 (chylomicrons) and ApoB100 (VLDL) and MTP play a crucial role in

Answer 19

lipoprotein assembly

Question 20

in the endoplasmic reticulum what is added to ApoB by MTP as it is being made and what does this form

Answer 20

lipids are added to ApoB and this forms a small lipopotein

Question 21

when a small lipoprotein particle is formed from lipids being added to ApoB, what does MTP add to make the particle bigger

Answer 21

triglycerides

Question 22

what occurs in the golgi before ApoB is secreted

Answer 22

glycosylation

Question 23

lipids combine with what via MTP in the ER to form chylomicrons

Answer 23

ApoB

Question 24

where are chylomicrons secreted from and what do they enter

Answer 24

from intestinal cells entering the bloodstream and lymphatic system

Question 25

what gives plasma a milky appearance after a fat rich meal and what is this due to

Answer 25

chylomicrons can give plasma a milky appearance due to high triacylglycerol content

Question 26

chylomicrons and VLDL are metabolised similarly by what

Answer 26

by lipoprotein lipase

Question 27

what does lipoprotein lipase do and where does this occur

Answer 27

hydrolyses the fatty acids, this occurs at the surface of tissues

Question 28

what does hepatic lipase (HTGL) do

Answer 28

generates LDL

Question 29

what dies LRP bind to

Answer 29

apoE

Question 30

what does LDLR bind to

Answer 30

apoB

Question 31

what receptor family are LRP and LDLR members of

Answer 31

LDL receptor family

Question 32

what do LRP and LDLR do

Answer 32

take up remnant IDl and LDL particles

Question 33

what is the function of lipoproteins

Answer 33

solubilise lipids for transport in blood to tissues

Question 34

what apoprotein is important for assembly

Answer 34

apoB

Question 35

what apoproteins are important for ligand cell surface receptors

Answer 35

apoB and apoE

Question 36

what apoprotein is important for enzyme cofactors

Answer 36

apoCII (for lipoprotein lipase)

Question 37

what are factors that affect lipids levels

Answer 37

diet = saturated vs unsaturated fats drugs = fibrates and statins genetics = defects in lipid metabolism disease = diabetes

Question 38

diets rich in what are LDL cholesterol lowering

Answer 38

diets rich in plant sterols

Question 39

what are mediterranean diets found to reduce

Answer 39

cardiac mortality

Question 40

eating high amounts of saturated fats can do what

Answer 40

cause LDL levels to increase

Question 41

what do statins do to LDL cholesterol

Answer 41

lower intracellular levels so the body makes more receptors meaning there is more LDL uptake

Question 42

what does ezetimibe do to LDL cholesterol

Answer 42

less cholesterol coming into the body as decreased intestinal uptake, so more LDL receptors

Question 43

fibrates and PUFAs both activate a what and what does this bind to and what does this switch on (example)

Answer 43

transcription factor, binds to response element and switching on many genes one of these is lipoprotein lipase which hydrolyses VLDL and chylomicrons

Question 44

what would a defect in LPL or apoC-II cause

Answer 44

elevated triglyceride levels

Question 45

what would a defect in apoB or MTP cause

Answer 45

low blood cholesterol levels