Lipid synthesis and transport in the blood Flashcards
What enzyme catalyses the first reaction in fatty acid synthesis
Acetyl CoA carboxylase converts acetyl CoA to malonyl CoA using ATP
What effect does malonyl CoA have on carnitine transferase and why
Inhibits it to stop entry of FA into mitochondria for B-oxidation - no point in making it if it is immediately used up.
How does proportion of fat/protein affect density of lipoprotein
proteins increase density
lipids decrease density
What is the structure of a lipoprotein
Inner core of triglycerides and cholesterol
outercore of phospholipids, cholesterol and apoproteins
What is the function of apoproteins
Activates enzymes in lipid metabolsim + recognised by receptors
Describe the transport of exogenous fats in the body
Chylomicrons affected by lipoprotein lipase (takes fatty acids of TAG, then glycerol goes back to liver. In adipocyte new glycerol is synthesised from glucose to make TAG to be stored)
Lipoprotein lipase activated by apo-C-II or insulin. Apo-C-II removed when it activates the enzyme, when it is removed from the chylomicron the chylomicron is now called a chylomicron element, which goes back to the liver.
What apoprotein is important in the transport of endogenous fats?
B-100
How does cholesterol control it’s own synthesis
Cholesterol free in the cell enters the nucleus and inhibits production of enzymes involved in its synthesis
Describe the pathway for cholesterol synthesis
Acetyl CoA + acetoacyl CoA
HMG-CoA
(rate limiting, HMG-reductase)
mevalonate I
Cholesterol
What inhibits HMG CoA reductase
statins
What do LDL receptors do
Recognise B-100 therefore removing LDLs from circulation via receptor mediated endocytosis
What causes familial hypercholesterolaemia
deficiency of LDL receptors as LDL levels will continue to rise
What do high levels of lipoprotein A lead to
LPA is thrombogenic
high conc assoc with increased risk of CHD
