Lecture 19/20: Classes of Cellular Lipids and Glycerophospholipid/Sphingolipid Synthesis Flashcards Preview

SMP - MNE Exam 1 > Lecture 19/20: Classes of Cellular Lipids and Glycerophospholipid/Sphingolipid Synthesis > Flashcards

Flashcards in Lecture 19/20: Classes of Cellular Lipids and Glycerophospholipid/Sphingolipid Synthesis Deck (59)
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1

What are the 2 mechanisms to synthesize glycerophospholipids from phosphatidic acid?

1. Activated diacylglycerol
2. Activated head groups

2

What is CDP?

Cytidine diphosphate

3

Describe the synthesis of glycerophospholipids using an activated diacylglycerol.

1. Activate the DAG with CDP
2. Head group then attacks the CDP-DAG

4

Describe the synthesis of glycerophospholipids using an activated head group.

1. Activate the head group with CDP
2. DAG then attacks the CDP-head group

5

What mechanism do bacteria, fungi, and mammals use to synthesize cardiolipin? Describe the 4 steps.

CTP activated DAG:
1. Phosphatidic acid + CTP = CDP-DAG + PPi
2. Add glycerol-3-phosphate + dephosphate: phosphatidylglycerol = PG
4. PG + PG = cardiolipin

6

What mechanism do bacteria and fungi use to synthesize phosphatidylserine? Describe the 2 steps.

CTP activated DAG:
1. Phosphatidic acid + CTP = CDP-DAG + PPi
2. CDP-DAG + serine = phosphatidylserine + CMP

7

What mechanism do bacteria and fungi use to synthesize phosphatidylethanolamine? Describe the 2 steps.

CTP activated DAG:
1. Make phosphatidylserine
2. PS decarboxylase = CO2 + phosphatidylethanolamine

8

What mechanism do bacteria, fungi, and mammals use to synthesize PG? Describe the 3 steps.

CTP activated DAG:
1. Phosphatidic acid + CTP = CDP-DAG + PPi
2. Add glycerol-3-phosphate + dephosphate: phosphatidylglycerol = PG

9

What mechanism do fungi and mammals use to synthesize phosphatidylinositol? Describe the 4 steps.

CTP activated DAG:
1. Make PG
4. PG + inositol-4,5-BP = phosphatidylinositol-4,5-BP

10

What mechanism do fungi use to synthesize phosphatidylcholine? Describe the 2 steps. What other mammal organ can do this?

CTP activated DAG:
1. Make phosphatidylethalonamine
2. Methylate it
LIVER!

11

What mechanism do mammals use to synthesize phosphatidylcholine? Describe the 1 step.

Head group activation:
CDP-choline + DAG = phosphatidylcholine

12

What mechanism do mammals use to synthesize phosphatidylethanolamine? Describe the 1 step.

Head group activation:
CDP-ethanolamine + DAG = phosphatidylethanolamine

13

What mechanism do mammals use to synthesize phosphatidylserine? Describe the 1 step

Head-group exchange mechanism:
CDP-serine + PE OR PC = phosphatidylserine

14

What is the role of surfactant?

Reduce surface tension in the alveoli during respiration to allow the alveoli to expand

15

What are the 2 major components of surfactant?

2 glycerophospholipids:
1. Dipalmitoylphosphatidylcholine (DPPC)
2. Unsaturated phosphatidylcholine

16

When does the fetus produce surfactant?

35 weeks

17

What is respiratory distress syndrome? Treatment?

Syndrome due to lack of surfactant in premature babies
Treatment: artificial lung surfactant and O2

18

What can be measured to understand the maturity of the surfactant being produced by a premature baby? Describe the interpretation of the results.

Measure L/S ratio = L-phosphatidylcholine/S-sphingomyelin ratio:
- Normal term pregnancy: >=2
- 1.5-2: 40% chance of developing respiratory distress syndrome

19

What are 2 ether-linked glycerophospholipids? What is the difference with normal glycerophospholipids?

1. Plasmalogens
2. Platelet-activating factor
They have an ether-linked alkane/alkene chain instead of an FA at position 1

20

What are the 2 possible head groups for plasmalogens?

1. Choline
2. Ethanolamine

21

What are plasmalogens important for? 3 things

1. Cardiac muscle tissues
2. Myelin sheath
3. Biomarker for metastatic cancers

22

Where is the double in plasmalogens? What do we call these molecules?

Between C1 and C2 of the alkene chain
Vynil ethers

23

Describe the composition of the platelet-activating factor. What does the position 2 portion of it allows it do to?

1. Ether linked alkane chain at position 1
2. Acetyl ester at position 2: small group allowing the molecule to circulate and be soluble in blood
3. Phosphocholine head group at position 3

24

What are the 2 roles of platelet activating factor?

1. Promotes aggregation of platelets
2. Promotes serotonin release from platelets for vasoconstriction
3. Important for inflammation and allergic responses

25

How is platelet-activating factor deactivated?

By removing the acetyl ester at the C2 position

26

Which one sphingolipid a phospholipid?

Sphingomyelin (with phosphocholine as a head group)

27

Describe the 3 steps of sphingolipid synthesis.

1. Sphingamine synthesis
2. Sphingamine + FA-CoA = N-acyl sphinganine (FA added to the amine group of the serine on C2)
3. Mixed-function oxidase: double bond introduced between C4 and C5 = ceramide

28

Describe the 2 steps of sphingamine synthesis. Describe sphingamine.

1. Palmitoyl-CoA + serine = β-ketosphingamine
2. β-ketosphingamine + NADPH = sphingamine (C=O reduced to C-OH): 18 C amino alcohol

29

What is the precursor to all of the sphingolipids?

Ceramide

30

Where does ceramide synthesis take place?

SER