Fatty Acid and TAG Synthesis

Question 0

<p>Major sites of Fatty acid synth </p>

Answer 0

<p>Liver, lactating mammary gland</p>

Question 1

Essential fatty acids

Answer 1

Needed in diet
Linoleic acid 18:2(9,12)
Linolenic acid 18:3(9,12,15)
If Linoeic isn’t around arachadonic is essential

Question 2

<p>Minor sites of Fatty acid synth</p>

Answer 2

<p>Kidney adipose tissue </p>

Question 3

<p>Coenzymes needed for FA Synth?</p>

Answer 3

<p>Acetyl CoA (pantothenic acid) ATP NADPH CO2 </p>

Question 4

<p>Where in the cell does FA synth take place?</p>

Answer 4

<p>Cytoplasm</p>

Question 5

<p>How does acetyl CoA get to the cytoplasm</p>

Answer 5

<p>Citrate shuttle </p>

Question 6

<p>When does FA synth take place?</p>

Answer 6

<p>When ATP is high and inhibits isocitrate dehydrogenase </p>

Question 7

How is citrate made from acetyl CoA?

Answer 7

Addition to oxaloacetate by citrate synthase

Question 8

What enzyme catalyzes the rate limiting step of FA synth?

Answer 8

Acetyl CoA carboxylase (requires biotin) and 1 ATP per malonyl CoA formed

Question 9

How is the active ACC different from the inactive?

Answer 9

Active is polymer

Inactive is dimer

Question 10

Name one positive and one negative allosteric modifier of ACC.

Answer 10

+=citrate (substrate activation)

-=palmitoyl CoA (product inhibition)

Question 11

How is ACC regulated hormonally?

Answer 11

Inactivated by phosphorylation (by glucagon, epinephrine, norepinephrine)

Question 12

What effect does a high fat diet have on ACC? (Same as fasting and glucagon)

Answer 12

Down regulation, decreased synthesis of FA

Question 13

What effect does a high carb fat free diet have on ACC?

Answer 13

Up regulated, more FA made

Question 14

Step 1 of FA Synth

Answer 14

Acetyl CoA added to cysteine of condensing arm of FA synthase

Question 15

Step 2 of FA synth?

Answer 15

Malonyl CoA added to ACP sulfhydryl group
(Takes 2 to tango; second substrate Added to A
Cuban Pedro)

Question 16

Step 3 of FA synth?

Answer 16

Acetyl condensing group adds to malonyl acyl Carrier

Question 17

Step 4 of FA synth?

Answer 17

Keto group is reduced (adds a hydroxyl group)

Question 18

Step 5 of FA synth?

Answer 18

Dehydrated to make trans monounsaturated fatty acyl group

Question 19

6th step of FA synth?

Answer 19

NADPH is used to reduce the double bond, leaving a saturated fatty acyl group to be transferred to the condensing enzyme SH

Question 20

Mnemonic for FA synthase steps

Answer 20

Aaron Makes Terrible Remembering Devices…Not!

Question 21

What enzyme releases palmitoyl-ACP from the FA synthase?

Answer 21

Thioesterase

Question 22

Where does FA chain elongation occur?

Answer 22

ER

Question 23

What double bonds can be formed by the three human fatty acid desaturases?

Answer 23

5, 6, or 9

Question 24

What 3 things does the fatty acid desaturase system need?

Answer 24

Cytochrome b5
Desaturase
NADPH-cytochrome b5 reductase

Question 25

Where can TAGs be made?

Answer 25

Liver and adipose tissue

Question 26

TAG synthesis step one makes….

Answer 26

Lysophosphatidic acid (glycerol phosphate with 1 FA added)

Question 27

Step 2 of TAG synthesis makes….

Answer 27

Phosphatidic acid (glycerol phosphate plus two FAs)

Question 28

Step 3 of TAG synthesis makes….

Answer 28

DAG (by removing the phosphate to make room for a third FA to be added next)

Question 29

Step 4 of TAG synthesis makes…

Answer 29

TAG!

Question 30

What enzyme catalyzes each step of TAG synthesis?

Answer 30

1, 2, & 4 = acylytransferase

3= phosphatase

Question 31

Where are chylomicrons made?

Answer 31

Intestinal mucous cells

Question 32

MT

What is the cellular location of citrate lyase? What irreversible reaction does it catalyze?

Answer 32

Cytosol

Citrate + ATP ➡️ oxaloacetate+ Ac-CoA + ADP + Pi

Question 33

MT

What is the cellular location and reaction catalyzes by the malic enzyme?

Answer 33

Malate + NADP ➡️ Pyruvate + CO2 + NADPH