Cholesterol Flashcards
What is cholesterol synthesised from?
Acetyl-CoA
What are the three main parts of cholesterol biosynthesis?
Generation of isopentyl pyrophosphate from acetyl-CoA Generation of squalene from isopentyl pyrophosphate Generation of cholesterol from squalene
What steroid hormone precursor is derived from cholesterol?
Pregnenolone – gives rise to all 5 types of steroid hormone
What Vitamin is synthesised from cholesterol?
Vitamin D
What breakdown products of cholesterol are used as bile salts?
Taurocholate and Glycocholate
Describe the role of cholesterol in signalling.
Cholesterol and sphingolipids form lipid rafts that are involved in localising proteins involved in signalling
What do the phospholipid monolayers of lipoproteins consist of?
Phospholipids
Cholesterol
Apoproteins
What is contained in the core of a lipoprotein?
Cholesteryl ester
Triacylglycerols
How are lipoproteins categorised?
Based on density Chylomicrons Very Low Intermediate Low High
Where is lipoprotein lipase found and what does it do?
It is found in capillary endothelial cells
Hydrolyses triacylglycerols to glycerol and fatty acids
Fatty acids are then used in beta-oxidation
What is the role of apoproteins in lipoproteins?
Allows the lipoprotein to be recognised by tissues
What are the clinical features of familial hypercholesterolaemia?
High risk of severe atherosclerosis and coronary infarction in adolescence
What mutation causes FH?
LDLR (LDL receptor)
How do statins reduce the accumulation of cholesterol? Give an example.
Statins are HMG-CoA Reductase inhibitors
Lovastatin – competitively inhibits HMG-CoA Reductase
What do Resins and Sequestrants do?
Hide bile acid-cholesterol complexes and prevents reabsorption by the intestines
Lowers LDL levels
Raises HDL levels
