Lipid metabolism

Question 1

Major components of dietary fat

Answer 1

Triglycerides(triacyglycerols), Cholesterol

Question 2

Problem of dietary fat

Answer 2

1. Dietary fat must be digested, absorbed by body and transported to cells that need it
2. Fats are insoluble in water

Step 1: Dietary trigycerides are substrates for lipases in the lumen of the gut, acting at a special amphipathic interface.

Question 3

TG digestion takes place in duodenum w assistance of bile salts

Answer 3

• Bile salts are secreted by liver and stored temporarily in the gall bladder
• Bile salts are chemically derived from cholesterol
• Bile salts emulsify TG into lipid droplets
• Pancreas secretes lipase which hydrolyses TG and diglycerides

Question 4

Digestion of TG by lipase is activated at…

Answer 4

the micelle lipid interface

Question 5

Beta oxidation

Answer 5

each round 1 NADH, 1FADH2, 1 Acetyl-CoA
TCA: 3NADH, 1FADH2, 1 GTP
TOTAL: 4NADH, 2FADH2, 1GTP
Single palmitate FA (16C) yields 106 ATP

Question 6

Odd chain FA oxidation leads to ..

Answer 6

Propionyl-CoA

–>converted to succinyl-CoA in 3 steps—>succinyl CoA converted to acetyl-CoA and enters TCA

Question 7

Succinyl-coA is converted to pyruvate before entering TCA as acetyl-CoA

Answer 7

malate—-(NADP+–>NADPH)—–>( )—(CO2)—->Pyruvate

Question 8

Peroxisomal beta oxidation of FA

Answer 8

Differs slightly from mitochondrial betaoxidation
shortens v long chain FA
Chain shortened acyl-CoAs are converted to carnitine esters and are passively diffused out of peroxisome to mitochondrion
in plants, FA oxidation occur exclusively in peroxisomes