In figure C the regulation of cholesterol synthesis by LDL is normal cells is co
ID: 68299 • Letter: I
Question
In figure C the regulation of cholesterol synthesis by LDL is normal cells is compared with cells from FH and . Why does increasing the external LDL concentration inhibit cholesterol synthesis in normal cells but not affect it in cells from FH or JD? Figure C) Regulation of cholesterol synthesis by LDL How would you expect the rate of cholesterol synthesis to be affected if normal cells and cells from FH or JD were incubated with cholesterol itself? (Remember, free cholesterol crosses the plasma membrane by diffusion.)Explanation / Answer
Cholesterol synthesis in normal cells can be inhibited when the cell concentration of LDL is high in the cell- hence in presence of high LDL concentration in the serum, the LDL can be readily taken in by the cell via LDL receptors & cholesterol synthesis can be restricted.
In Familial Hypercholesterolemia (FH), where mutations affect the LDL receptor, the LDL molecules cannot be uptaken by the cells even in presence of high LDL concentration. So, there is no inhibition of cholesterol synthesis.