Lecture 13 - Synthesis of Triacylglycerides and Phospholipids

Question 1

Step 1a

Answer 1

Glycerol -> glycerol phosphate

Question 2

Enzyme of step 1a

Answer 2

Glycerol kinase

Question 3

Cofactor of step 1a

Answer 3

ATP -> ADP

Question 4

Where does step 1a occur?

Answer 4

Liver

Question 5

Step 1b

Answer 5

Dihydroxyacetone phosphate -> glycerol phosphate

Question 6

Enzyme of step 1b

Answer 6

Glycerol-3-phosphate dehydrogenase

Question 7

Cofactor of step 1b

Answer 7

NADH + H+ -> NAD+

Question 8

Where does step 1b occur?

Answer 8

Intestines

Question 9

Step 2

Answer 9

Glycerol phosphate -> diacyl phosphatidate

Question 10

Enzyme of step 2

Answer 10

Glycerol phosphate acyl transferase

Question 11

Cofactor of step 2

Answer 11

2 fatty acyl-CoA -> 2 CoA-SH

Question 12

Step 3

Answer 12

Diacyl phosphatidate -> diacylglyceride

Question 13

Enzyme of step 3

Answer 13

Phosphatidate phosphatase

Question 14

Cofactor of step 3

Answer 14

H2O -> Pi

Question 15

Which structures enter a different pathway for phospholipid synthesis?

Answer 15

• Diacyl phosphatidate enters route A

- Diacylglyceride enters route B

Question 16

Step 4 (triacylglyceride synthesis)

Answer 16

Diacylglyceride -> triacylglyceride

Question 17

Enzyme of step 4 (triacylglyceride synthesis)

Answer 17

Diacylglyceride acyl transferase

Question 18

Cofactor of step 4 (triacylglyceride synthesis)

Answer 18

Fatty acyl-CoA -> CoA-SH

Question 19

What is needed for phospholipid synthesis?

Answer 19

Activation by CDP (CDP-diacylglycerol for pathway A; CDP-head group for pathway B)

Question 20

Pathway A occurs in _____ and ____

Answer 20

Bacteria and yeast

Question 21

Pathway B occurs in ____

Answer 21

Mammals

Question 22

Is synthesis of phospholipids the same in mammals as it is in yeast and bacteria?

Answer 22

Nope

Question 23

Step 1 of route A to phospholipids

Answer 23

Diacyl phosphatidate -> CDP diacylglycerol

Question 24

Enzyme of step 1 of route A to phospholipids

Answer 24

Phosphatidase cytidylyl transferase

Question 25

Cofactor of step 1 of route A to phospholipids

Answer 25

CTP -> PPi -> 2 Pi

Question 26

Is CDP diacylglycerol activated or inactivated diacylglycerol?

Answer 26

Activated

Question 27

Step 2 of route A to phospholipids

Answer 27

CDP diacylglycerol -> phosphatidylserine

Question 28

Cofactor of step 2 of route A to phospholipids

Answer 28

Serine -> CMP

Question 29

Enzyme of step 2 of route A to phospholipids

Answer 29

CDP diacylglycerol serine-O-phosphatidyl transferase

Question 30

Step 3 of route A to phospholipids

Answer 30

Phosphatidylserine -> phosphatidylethanolamine

Question 31

Enzyme of step 3 of route A to phospholipids

Answer 31

Phosphatidylserine decarboxylase

Question 32

Cofactor of step 3 of route A to phospholipids

Answer 32

CO2 out

Question 33

Step 1 of route B to phospholipids

Answer 33

Choline -> phosphocholine

Question 34

Enzyme of step 1 of route B to phospholipids

Answer 34

Choline kinase

Question 35

Cofactor of step 1 of route B to phospholipids

Answer 35

ATP -> ADP

Question 36

Step 2 of route B to phospholipids

Answer 36

Phosphocholine -> CDP-choline

Question 37

Enzyme of step 2 of route B to phospholipids

Answer 37

Phosphocholine cytidylyl transferase

Question 38

Cofactor of step 2 of route B to phospholipids

Answer 38

CTP -> PPi -> 2 Pi

Question 39

Step 3 of route B to phospholipids

Answer 39

CDP-choline -> phosphatidylcholine

Question 40

Enzyme of step 3 of route B to phospholipids

Answer 40

Phosphocholine transferase

Question 41

Cofactor of step 3 of route B to phospholipids

Answer 41

Phospholipid -> CMP

Question 42

What is the main difference between the synthesis of phospholipids in mammals and yeast/bacteria?

Answer 42

• Yeast and bacteria use “activated” diacylglycerol

- Mammals use “activated” head group