Lipid transport and FA oxidation

Question 1

triacylglycerol’s, cholesterol esters, phospholipids are broken down by

Answer 1

lipases, cholesterol esterase, phospholipase A2

Question 2

the function of lipoproteins

Answer 2

is to transfer lipids between the intestines, liver and other tissues

Question 3

triacylglycerol’s are

Answer 3

FA esters of glycerol

Question 4

how are TAG absorbed

Answer 4

• They are not emulsified in the stomach
• they are emulsified in the duodenum by phosphatidylcholine and bile acids
• TAGs are hydrolyzed by pancreatic lipase to form FFA, DAG, MAG
• if <10C FFA they enter enterocytes by diffusion
• if >10C FFA they form mixed micelles with phosphatidyl choline and bile acids
• in the intestine FFA form a complex with intestinal fatty acid binding protein I-FABP which helps protect the cell from harmful activity of FFA
• in enterocytes FFA are assembled in TAG which then form chylomicrons

Question 5

where do lipases act

Answer 5

at the lipid-water interface

Question 6

what is the function of phospholipases

Answer 6

they hydrolyze glycerophospholipids, into lysophospholipids

Question 7

LDL

Answer 7

have cholesterol esters, apoliprotein B-100, phospholipid, unesterified cholesterol

Question 8

what happens to chylomicrons

Answer 8

they are released from the intestine into the lymphatics and they bypass the liver

Question 9

the function of HDL

Answer 9

transport cholesterol from tissues to liver

Question 10

how do FFA circulate in the body

Answer 10

FA are bound to albumin , glycerol is free

Question 11

what are the fates of glycerol (which roams free in the blood)

Answer 11

enter gluconeogenesis or glycolysis

Question 12

FA to be degraded/oxidized are linked to - in an ATP dependent reaction

Answer 12

coA

Question 13

how are fatty acyl groups transported into the mitochondria

Answer 13

via a carnitine shuttle for oxidation

Question 14

every round of mitochondrial beta oxidation produces

Answer 14

FADH2, NADH, acetyl-coA

Question 15

what happens to the propionyl-coA produced by the oxidation of odd-chain FA

Answer 15

it is converted to succinyl-coA

Question 16

what oxidizes long chain FA

Answer 16

peroxisomes and they produce H2O2

Question 17

what does acyl coA synthetase do and where

Answer 17

in the cytosol, it condenses FA with coA and hydrolyses ATP to AMP

Question 18

what is the function of carnitine

Answer 18

is carries acyl groups across the inner m membrane

• short chain FA are carried directly into the matrix
• long chain FA are converted to acyl carnitines first

Question 19

where are acyl-coA esters made

Answer 19

inside the inner membrane of the mitochondria

Question 20

what is the function of acyl coA DH

Answer 20

oxidation of the C alpha-C beta bond, it involves proton abstraction and hydride removal by FAD, e are transferred to flavoprotein and then to the ETC

Question 21

what is the function of enoyl-coA hydratase

Answer 21

adds water to the double bond, converts trans-enoyl coA to L-beta hydroxyacyl coA

Question 22

what is the function of hydroxyacyl coA DH

Answer 22

oxidises the beta hydroxyl group

Question 23

what is the function of thiolase

Answer 23

it is the reverse of a claisen condensation reaction

Question 24

oxidation of palmitic acid forms - acetyl coA, and - ATP

Answer 24

8, 106

Question 25

oxidation of odd chain FA yeilds

Answer 25

propionyl coA

Question 26

what is the function of methylmalonyl coA

Answer 26

it causes a skeletal rearrangement of methylmalonyl coA into succinyl coA

Question 27

is succinyl coA directly consumed by TCA

Answer 27

no it is converted to malate then to pyruvate

Question 28

the beta oxidation of very long FA >22C and branched FFA happens where

Answer 28

in the peroxisomes

Question 29

what are ketone bodies

Answer 29

a source of fuel and energy

• some acetyl coA made by FA oxidation in liver mitochondria is converted to acetone, acetoacetate, beta hydroxybutyrate (ketone bodies)
• these are transportable forms of FA