Chapter 24 (Cholesterol)

Question 1

Cholesterol is only generated by ___

Answer 1

animals

Question 2

Cholesterol is weakly amphiphilic because of the lone ___

Answer 2

hydroxyl group

Question 3

Cholesterol is a precursor to three things

Answer 3

steroids
bile salts
Vitamin D

Question 4

A deficiency in Vitamin D can lead to:

Answer 4

Rickets

synthesized by sunlight

Question 5

___ is the primary tissue for cholesterol synthesis

Answer 5

Liver (cytosol)

Question 6

When we want to inhibit cholesterol synthesis we focus on the enzyme:

Answer 6

HMG-CoA Reductase (first committed step)

Done so by using Statins

Question 7

Lovastatin

Answer 7

An inactive lactone that acts as an inhibitor to HMG-CoA Reductase
The lactone is hydrolyzed to mevinolinic acid, which is a competitive inhibitor or reductase

Question 8

HMG-CoA Reductase is inactivated by

Answer 8

phosphorylation by cAMP-dependent kinases

Question 9

Prenyltransferase is a ___ condensation reaction

Answer 9

head-to-tail

Question 10

Synthesis of cholesterol from Squalene takes place here

Answer 10

endoplasmic reticulum membrane

Question 11

LDL’s transport:

Answer 11

cholesterol to the tissues that need it

Question 12

Why are LDL’s considered to be the “bad” type of cholesterol

Answer 12

because as they circulate they are subjected to oxidation
Too much oxidation leads to them not being able to bind to receptors
They become seen as foreign and turn into plaque

Question 13

Chylomicrons

Answer 13

Produced by the intestinal mucosal cells

Has the lowest density

Question 14

HDL’s role

Answer 14

Picks up excess cholesterol from the tissues and transports it back to the liver

Question 15

All lipoproteins have this

Answer 15

hydrophobic interiors

Question 16

When lipoproteins have a high TAG content this means they have: (trend)

Answer 16

low density

Question 17

Which lipoprotein has the highest concentration of cholesterol esters

Answer 17

LDL’s

Question 18

What determines the density of lipoproteins

Answer 18

protein content (higher content = higher density)

Question 19

Extra cholesterol gets turned into:

Answer 19

bile salts

Question 20

Chylomicrons get these when they bump into HDL’s

Answer 20

Apo C-II

Question 21

LDL binding domain on ___

Answer 21

N-Terminus

Question 22

Dysfunctions in or absence of LDL receptors lead to:

Answer 22

familial hypercholesterolemia

Question 23

Which is worse: Hetero or Homozygous familial hypercholesterolemia

Answer 23

Homozygous

Requires a liver transplant since around 95% of LDL receptors are located on the liver

Question 24

Excess cholesterol is converted into ___ acid and ___ inhibits this step

Answer 24

Cholic Acid (bile salt)
Trans-fatty Acids

Question 25

Low cholesterol levels will prevent 3 things

Answer 25

1. absorption of cholesterol in SI
2. liver synthesis of cholesterol
3. absorption of bile salts in LI

Question 26

Bile acids solubilize ___

Answer 26

ingested fats