Ch5: Cholesterol

Question 1

Does dietary cholesterol have effect on blood cholesterol levels?

Answer 1

No, this only has a minor effect on blood cholesterol levels

Question 2

Where is cholesterol found?

Answer 2

Found in Cell membranes
Serves as the precursor for many important steroids such as bile acids, steroid sex hormones and fat soluble vitamins

Question 3

What is the general structure of cholesterol?

Answer 3

Carbon rings and a carbon chain attached

Question 4

What is the first step of cholesterol biosynthesis?

Answer 4

Acetyl-CoA + Acetoacetyl-CoA
↓
HMG-CoA

Question 5

What is the second step of cholesterol biosynthesis?

Answer 5

HMG-CoA
↓ HMG-CoA Reductase
Mevalonate

Question 6

What is the third step of cholesterol biosynthesis?

Answer 6

Mevalonate
↓
↓
↓
Farnesyl-PP

Question 7

What is the fourth step of cholesterol biosynthesis?

Answer 7

Farnesyl-PP
↓
Squalene

Question 8

What is the fifth step of cholesterol biosynthesis?

Answer 8

Squalene
↓
Cholesterol -> lipoprotein, vitamin D, bile acids, steroid hormones

Question 9

Where does cholesterol synthesis occur?

Answer 9

Primary synthetic sites are extrahepatic (outside the liver)
But the liver is key regulator of homeostasis

Question 10

What is the importance of cholesterol?

Answer 10

It is important for animal cell structure
Also serves as a precursor for the biosynthesis of steroid hormones and bile acids

Question 11

What is the largest source of cholesterol that enters the small intestine?

Answer 11

Biliary secretion(released by the liver), not the diet

Question 12

What is the normal amount of cholesterol absorbed?

Answer 12

50%
The cholesterol that is not absorbed is excreted in the feces