Lipid Metabolism

Question 1

What fatty acids can’t we synthesise?

Answer 1

Omega 3 and Omega 6

Question 2

What are three things we need cholesterol for?

Answer 2

Steroid hormones, bile acids, membrane components.

Question 3

Lipids as a whole - what do we need them for?

3 are cholesterol based.

Answer 3

1. energy (obviously)
2. thermal insulation
3. mechanical protection for vital organs
4. bile acid synthesis (absorption of fat soluble vitamins)
5. steroid hormone synthesis
6. cell membrane components

Question 4

What is partial dehydrogenation of vegetable oils and what are the commercial benefits of doing it?

Answer 4

That’s the one that creates trans double bonds.
It extends the shelf life and
increases stability at high temperatures.

Question 5

Triglycerides are fatty acid _________ of glycerol.

Answer 5

Triesters.

Question 6

Phospholipids are like triglycerides but they have two ___________ groups and one ___________ group.

Answer 6

2 x fatty acid groups
1 x phosphate group*

*or sphignosine group

Question 7

Why are cholesterol esters a thing in lipid metabolism?

Answer 7

Free cholesterol is entropically relegated to the surface of cells or transport vessels (they are poorly soluble). Esterifying cholesterol with a fatty acid moiety allows for localisation to the core and substantially increases the carrying capacity of the body’s lipoproteins.

Question 8

Cholesterol esters are formed between the ___________ group of cholesterol and the _____________ group of a _____________.

Answer 8

hydroxyl group of a cholesterol

carboxylate group of a fatty acid

Question 9

What process does LCAT catalyse?

Answer 9

The esterification of cholesterol and fatty acid moieties. (Formation of cholesterol esters).

Question 10

There are seven different sizes of LDL. The ________ ones are dangerous; the ________ ones are less associated with atherosclerosis.

Answer 10

Smaller LDLs are more dangerous.

Larger LDLs aren’t associated with atherosclerosis.

Question 11

For reinforcement: The ________ an LDL is, the more they are associated with atherosclerosis.

Answer 11

SMALLER [diameter] LDLs are more dangerous.

Question 12

The _________ pathway starts from the intestines and uses ApoB___. The _________ pathway starts from the liver and uses ApoB___.

Answer 12

Extrinsic - intestines - ApoB48.

Intrinsic - liver - ApoB100.

Question 13

LDLs carry __% of plasma cholesterol.

Answer 13

LDLs carry 70% of plasma cholesterol.

Question 14

ApoB-100 and ApoB-48 come from the same mRNA strand. In the intestine, ApoB-100 mRNA loses the carboxy portion coding for the ____ binding site.

Answer 14

LDLr - therefore ApoB-48 loses LDLr binding ability.

Question 15

Generally, triglycerides are taken up via a ___-mediated process and cholesterol is taken up via a ___-mediated process.

Answer 15

TGs: lipoprotein lipase (hydrolysis).
Cholesterol: LDLr (endocytosis).

Question 16

Bonus: accumulation of cholesterol by macrophages is not LDLr-mediated; it is unregulated processes of cholesterol accumulation into foam cells that leads to their development and the progression of atherosclerotic plaques. Typically, cholesterol uptake is LDLr mediated and therefore subject to the homeostatic processes surrounding intracellular [cholesterol].

Answer 16

Bonus: intracellular [cholesterol] upregulates ACAT, downregulates HMG-CoA reductase and downregulates LDLr expression.

Question 17

Hepatic triglycerides are transported to the periphery via the ______ pathway (ApoB-___). Dietary triglycerides are transported to the periphery via the ______ pathway (ApoB-__).

Answer 17

Hepatic; endogenous; ApoB-100

Dietary; exogenous; ApoB-48

Question 18

Chylomicrons enter circulation from the intestines first via the __________.

Answer 18

lymphatic system.

Question 19

IDL TAGs are hydrolysed at the liver by ________, converting the IDL to LDL.

Answer 19

hepatic lipase.

Question 20

According to the lecture table, ApoE is carried by…

Answer 20

… chylomicron remnants, IDLs and HDLs.

Question 21

What are the three components of an atherosclerotic plaque?

Answer 21

1. foam cells, SMC cells and T cells
2. ECM components - collagen, elastic fibres and proteoglycans
3. intracellular and extracellular lipids.

Question 22

What are the main cellular components of an atherosclerotic plaque?

Answer 22

foam cells
SCM and
T-cells.

Question 23

What are the major ECM components present in an atherosclerotic plaque?

Answer 23

collagen,
elastins and
proteoglycans

Question 24

Good word: hypercholesterolaemia is a/an _________ risk factor in atherosclerosis and CV events.

Answer 24

independent risk factor

Question 25

Plaques initiate when macrophages hunt oxidised LDLs in the _________.

Answer 25

media intima.