Lipids IV

Question 1

What are sphingolipidoses?

Answer 1

rare genetic disease

results in accumulation of undegraded glycolipids in the lysosomes of phagocytic cells

Question 2

What enzymatic defect is present in Tay-Sachs? What is the accumulated lipid?

Answer 2

beta-hexosaminidase.

ganglioside

Question 3

What enzymatic defect is present in Gaucher’s? What is the accumulated lipid?

Answer 3

beta-glucosidase or beta-cerebrosideas

GLUCOcerebroside

Question 4

What enzymatic defect is present in Fabry’s? What is the accumulated lipid?

Answer 4

alpha-galactosidase

ceramide trihexoside

Question 5

What enzymatic defect is present in Niemann-Pick? What is the accumulated lipid?

Answer 5

sphingomyelinase

sphingomyelin

Question 6

What enzymatic defect is present in Sandhoff Disease? What is the accumulated lipid?

Answer 6

beta-hexosaminidase A and B

gangliosides and globosides

Question 7

Metachromatic leukodystrophy

Answer 7

arylsulfatase

sulfatide

Question 8

What is the presentation of Gaucher’s Disease?

Answer 8

liver and spleen enlargement, erosion of long bones

Question 9

Where does the formation of ketone bodies occur? Where does the synthesis of cholesterol occur?

Answer 9

ketone bodies = mitochondria

cholesterol = cytosol

Question 10

When do the formation of ketone bodies and cholesterol diverge?

Answer 10

at the function of HMG-CoA Synthase

Question 11

What is the rate limiting step for the production of cholesterol?

Answer 11

HMG-CoA Reductase

Question 12

What does HMG-CoA Reductase produce? What does it use for a reducing equivalent?

Answer 12

mevalonic acid.

NADPH

Question 13

How is HMG-CoA Reductase regulated?

Answer 13

AMP-dependent kinase inactivates the enzyme

HMG-CoA Reductase is active when cellular energy is high

Question 14

How is HMG-CoA Reductase regulated hormonally?

Answer 14

Insulin dependent dephosphorylation activates the enzyme

Question 15

Does HMG-CoA Reductase experience end-product inhibition?

Answer 15

yes.

Question 16

What is the function of lecitin:cholesterol acyltransferase (LCAT)?

Answer 16

to esterify a long-chain acyl group to the C3 of cholesterol

Question 17

Where are cholesteryl esters found?

Answer 17

hydrophobic center of lipoproteins or fat droplets

Question 18

What three things need to happen to cholesterol in order to become a bile acid?

Answer 18

oxidation of C24

hydroxylation of C7 and C12

Question 19

Where does the liver synthesize and secrete bile acids?

Answer 19

the intestine

Question 20

Where does cholesterol synthesis take place? Where does ketone body synthesis take place?

Answer 20

cholesterol = cytosol

ketone body = mitochondria

Question 21

What mechanism separates ketone body synthesis from cholesterol synthesis?

Answer 21

HMG-CoA Synthase isoforms

Question 22

What is the rate limiting step for cholesterol synthesis?

Answer 22

HMG-CoA Reductase

Question 23

What carbon # of cholesterol is esterified ?

Answer 23

number 3

Question 24

What enzyme esterifies cholesterol?

Answer 24

LCAT

Question 25

What number carbon is oxidized to produce bile acids?

Answer 25

C24 is oxidized

Question 26

What carbon numbers of cholesterol are hydroxylated to produce bile acids?

Answer 26

C7 ad C12