Lecture 6

Question 1

What is lipogenesis

Answer 1

formation of lipids from CHO and proteins

Question 2

Where does lipogenesis occur?

Answer 2

cytoplasm

Question 3

What type of reactions occur in lipogenesis?

Answer 3

reductions (ie addition of H+ and use of NADPH

Question 4

What are the two proteins important in lipogenesis

Answer 4

ACP (acyl carrier protein) and CE (Condensing protein)

Question 5

What is the cofactor for CE protein?

Answer 5

cysteine

Question 6

What are the 3 important steps in lipogenesis?

Answer 6

Acetyl CoA to Malonyl ACP to palmitate 16:0

Question 7

What is the first fatty acid produced from glucose? Precursor to all other FAs

Answer 7

Palmitate

Question 8

What is lipolysis?

Answer 8

breakdown of triclycerides by lipases into glycerol and free fatty acids for energy

Question 9

what hormones activate and suppress lipolysis

Answer 9

epinpehrine and glucagon activate, insulin inhibits it.

Question 10

What are the enzymes involved in lipolysis?

Answer 10

Triacylglycerol lipase
diacylglycerol lipase
monoacylglycerol lipase

Question 11

Besides stimulating lipolysis, what other effect does insulin have on adipose cells/

Answer 11

inhibits the breakdown of fatty acid stores and increases stores.

Question 12

What is beta-oxidation?

Answer 12

The oxidation of fatty acids in the mitochondria to Acetyl CoA

Question 13

What is the carrier molecule for free fatty acids in beta oxidation

Answer 13

carnitine

Question 14

what are the stages of beta-oxidation?

Answer 14

fatty acid activation (allows fatty acids in cytosol to enter mitochondria for oxidation). Oxidation of fatty acids (removes 2 carbon segments, one at a time, from a fatty acid.

Question 15

What is the product of beta-oxidation?

Answer 15

Acetyl-CoA. This is shuttled into the krebs cycle and converted into energy (ATP)

Question 16

What is cholesterol the precursor to?

Answer 16

Steroids in the body (eg glucocorticoids (cotisol), mineralocorticoids (aldosterone),
Bile salts - emulsification/digestion
steroid sex hormones - androgens, oestrogens, progesterones. Vitamin D synthesis, structural integrity of cell membranes.

Question 17

How is cholesterol transported through the circulation/

Answer 17

lipoproteins

Question 18

what is the storage form of cholesterol (in cells)

Answer 18

cholesterol esters

Question 19

Where in the body does biosynthesis of cholesterol occur?

Answer 19

10% liver, 15% intestines

Question 20

where in the cell does cholesterol biosynthesis occur, and from what substance is it synthesised?

Answer 20

cytoplasm and microsomes (from acetyl CoA)

Question 21

What are the steps in cholesterol biosysthesis?

Answer 21

acetyl CoA 
HMG-CoA 
(HMG CoA reductase enzyme)
mevalonate
IPP
Squalene 
cholesterol

Question 22

What substance is produced by an intermediate to squalene in the cholesterol biosynthesis pathway?

Answer 22

CoQ10 (ubiquinone)

Question 23

What is the major carrier of endogenously produced cholesterol?

Answer 23

LDL

Question 24

How much cholesterol does LDL carry?

Answer 24

50%

Question 25

What are the anti-atherogenic properties of HDL?

Answer 25

antioxidative
anti-inflammatory
immunomodulation
improves endothelial function
anti-thrombotic

Question 26

How much cholesterol does VLDL carry?

Answer 26

25%