Lipid Metabolism Flashcards
What fatty acids can’t we synthesise?
Omega 3 and Omega 6
What are three things we need cholesterol for?
Steroid hormones, bile acids, membrane components.
Lipids as a whole - what do we need them for?
3 are cholesterol based.
- energy (obviously)
- thermal insulation
- mechanical protection for vital organs
- bile acid synthesis (absorption of fat soluble vitamins)
- steroid hormone synthesis
- cell membrane components
What is partial dehydrogenation of vegetable oils and what are the commercial benefits of doing it?
That’s the one that creates trans double bonds.
It extends the shelf life and
increases stability at high temperatures.
Triglycerides are fatty acid _________ of glycerol.
Triesters.
Phospholipids are like triglycerides but they have two ___________ groups and one ___________ group.
2 x fatty acid groups
1 x phosphate group*
*or sphignosine group
Why are cholesterol esters a thing in lipid metabolism?
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.
Cholesterol esters are formed between the ___________ group of cholesterol and the _____________ group of a _____________.
hydroxyl group of a cholesterol
carboxylate group of a fatty acid
What process does LCAT catalyse?
The esterification of cholesterol and fatty acid moieties. (Formation of cholesterol esters).
There are seven different sizes of LDL. The ________ ones are dangerous; the ________ ones are less associated with atherosclerosis.
Smaller LDLs are more dangerous.
Larger LDLs aren’t associated with atherosclerosis.
For reinforcement: The ________ an LDL is, the more they are associated with atherosclerosis.
SMALLER [diameter] LDLs are more dangerous.
The _________ pathway starts from the intestines and uses ApoB___. The _________ pathway starts from the liver and uses ApoB___.
Extrinsic - intestines - ApoB48.
Intrinsic - liver - ApoB100.
LDLs carry __% of plasma cholesterol.
LDLs carry 70% of plasma cholesterol.
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.
LDLr - therefore ApoB-48 loses LDLr binding ability.
Generally, triglycerides are taken up via a ___-mediated process and cholesterol is taken up via a ___-mediated process.
TGs: lipoprotein lipase (hydrolysis).
Cholesterol: LDLr (endocytosis).
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].
Bonus: intracellular [cholesterol] upregulates ACAT, downregulates HMG-CoA reductase and downregulates LDLr expression.
Hepatic triglycerides are transported to the periphery via the ______ pathway (ApoB-___). Dietary triglycerides are transported to the periphery via the ______ pathway (ApoB-__).
Hepatic; endogenous; ApoB-100
Dietary; exogenous; ApoB-48
Chylomicrons enter circulation from the intestines first via the __________.
lymphatic system.
IDL TAGs are hydrolysed at the liver by ________, converting the IDL to LDL.
hepatic lipase.
According to the lecture table, ApoE is carried by…
… chylomicron remnants, IDLs and HDLs.
What are the three components of an atherosclerotic plaque?
- foam cells, SMC cells and T cells
- ECM components - collagen, elastic fibres and proteoglycans
- intracellular and extracellular lipids.
What are the main cellular components of an atherosclerotic plaque?
foam cells
SCM and
T-cells.
What are the major ECM components present in an atherosclerotic plaque?
collagen,
elastins and
proteoglycans
Good word: hypercholesterolaemia is a/an _________ risk factor in atherosclerosis and CV events.
independent risk factor
Plaques initiate when macrophages hunt oxidised LDLs in the _________.
media intima.
