3.3 Lipid Catabolism

Question 1

fatty acid release def

Answer 1

the cytosolic breakdown of triglycerides (highly nonpolar so most of energy is stored in these fats) during starvation of glucose and glycogen by using lipase(responsible for cleaving ester bonds so that small intestine can absorb the substituents of the monoglycerol and fatty acids) through lipolysis

Question 2

fatty acid transport

Answer 2

• occurs in the cytosol
• covalently bonded to coenzyme A to make acetyl co A to activate it
• has a carnitine shuttle (moves from cytosol to mitochondrial matrix)

Question 3

what is coenzyme used for?

Answer 3

1. biosynthesis of fatty acids
2. oxidation of fatty acids
3. oxidation of pyruvate

Question 4

define lypolysis

Answer 4

lipase will break the parent triglycerides and will become desterfied/hydrolysed to get rid of ester bonds so that the new tryglycerides can be used to generate high energy when moved to the matrix of mitochondria BUT HAS NOT YET TRANSPORTED TO THE MATRIX DURING LYPOLYSIS

Question 5

what is the main purpose of the carnitine shuttle?

Answer 5

to take the newly formed tryglyceride from lipolysis from the cytosol to the matrix
-it also gives access to beta oxidation

Question 6

what is beta oxidation?

Answer 6

produces reduced cofactors FADH2 and NADH and acetyl coA

Question 7

what carbon number is beta on a fatty acid?

Answer 7

3

Question 8

appearance factors of coA

Answer 8

1. HS thiol group
2. at least one phosphate group
3. adenine

Question 9

what does brackets mean on fatty acids?

Answer 9

the number of repeated units

Question 10

fatty acid with 12 carbons and no double bonds?

Answer 10

protonated: lauric acid
ionized/ natural form: laurate
acyl group: lauryl

Question 11

fatty acid with 14carbons and no double bonds?

Answer 11

protonated: mryristic acid
ionized/ natural form: myristate
acyl group: miristyl

Question 12

fatty acid with 16 carbons and no double bonds?

Answer 12

protonated: palmitic acid
ionized/ natural form: paulmitate
acyl group: paulmyl

Question 13

fatty acid with 18 carbons and no double bonds?

Answer 13

protonated: stearic acid
ionized/ natural form: stearate
acyl group: stearyl

Question 14

triglycerol appearance

Answer 14

three carbonyl , three CH, three r groups and fatty acid part is carbonyl

Question 15

acetyl coA synthetase

Answer 15

acetyl group of fatty acid wants the phosphate group f atp and
when binded the thiol of S co A will do nucleophilic attack on carbon of mixe anhydride atp fatty acid

makes thiol

Question 16

carnitine acetyl transferase I

Answer 16

quaternary amine that will have acyl-CoA is first converted to acyl-carnitine by carnitine acyltransferase I—an enzyme located at the outer (intermembraneous space) surface of IMM—in order to exploit the carnitine shuttle system for its delivery into the mitochondrial matrix

Question 17

carnitine-acylcarnitine translocase

Answer 17

Acyl-carnitine is shuttled across the inner mitochondrial membrane (IMM)—from the cytosol (or the intermembraneous space) to the mitochondrial matrix

Question 18

carnitine acetyl transferase II

Answer 18

catalyzes the reverse transfer of acyl group of acyl-carnitine back to CoA to generate acylCoA and free carnitine

Question 19

what happens to the free carnitine

Answer 19

goes back to cytosol to be recycled

Question 20

acyl vs enoyl

Answer 20

acyl has 1 double bond bc of acetyl

enoyl will have 2 double bond

Question 21

acyl-CoA dehydrogenase

Answer 21

Dehydrogenation of saturated C-C single bond within acyl-CoA results in the formation of enoylCoA harboring a C=C double bond and requires strong FAD to make double bond of high energy

Question 22

hydration

Answer 22

Hydration of unsaturated C=C double bond within trans-2-enoylCoA (prochiral) results in the formation of L-beta-hydroxyacyl-CoA

Question 23

beta -Hydroxyacyl-CoA Dehydrogenase

Answer 23

usually involving keta it is NAD which reduces
Oxidation of –OH to a keto group at the C position within L-beta-hydroxyacyl-CoA results in the formation of corresponding ketoacyl-CoA

Question 24

beta Ketoacyl-CoA Thiolase

Answer 24

Thiolysis (or breaking bonds with –SH group—cf hydrolysis and phosphorolysis) initiated by nucleophilic attack of the thiol group (-SH) of CoA on the keto group within -ketoacyl-CoA results in the cleavage of C-C bond, thereby releasing the first acetyl-CoA

Question 25

for each round, how many of what?

Answer 25

1 acetyl coA, 1 NADH, 1FADH2

formula: n acetyl
n-1 for nadh and fadh2

Question 26

ex: 16 carbons gives how many of what?

Answer 26

6 rounds you removed 12 carbons ? final rounds give 2 acetyl coA so only total of 7 rounds?
8 acetyl co A
7 nadh and 7 fadh2