1.22

Question 1

regulation of cholesterol

Answer 1

• allosteric: (-) mevalonate and cholesterol
• reg. by phosphorylation: glucagon (inact)
• enzyme induction by thyroxine
  + reg. by dephosphorylation: insulin (act’9
  + enzyme depression by cortisol

Question 2

hepatic cholesterol uptake

Answer 2

LDL in liver; receptors for cholesterol in liver, will be taken up and cause high IC levels of cholesterol

Question 3

function of cholesterol

Answer 3

(taken up through diet of plant and animal origin)

• membrane
• prod. steroid hormones, bile acids, vit. D

Question 4

transport of cholesterol

Answer 4

esterified by FA of Leicithin (glycerophospholipid, hydrophilic and hydrophobic)

Question 5

where is cholesterol found in the body

Answer 5

in membrane and the blood

Question 6

storage of cholesterol

Answer 6

esterified by …?

Question 7

how are bile stones made

Answer 7

formed when cholesterol is solubilized in the bile by bile acid and lecithin

Question 8

primary bile acids

Answer 8

cholic acid, chenodeoxycholic acid

Question 9

secondary bile acids

Answer 9

deoxycholic acid, lithocholic acid

Question 10

how are bile acids..

Answer 10

1. cholesterol -> 1’ bile acid in cytoplasm of liver(conjugation)
2. enter intestines, where 7-OH is removed by microbial enzymes (de-conjugation), 2’ bile acid -> faeces or back to liver for removal of cholesterol

Question 11

functions of bile salts

Answer 11

• emulsification of fats: incr. surface area for lipase
• solublilize and tp. lipids in aqeous solutions(vit. absorption/tp., micelle formation)
• alter transcription of rate limiting enzyme in cholesterol synth.
• removal of cholesterol from body by synth into bile salts/acids