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Flashcards in Lipid synthesis Deck (58):
1

Synthesis of palmitate:

Has 16 carbons. Primary FA that we make; no DB's, fully saturated.

2

Where does most fatty acid synthesis take place

liver;

3

What does excess acetylCoA convert to?

Fatty acid esters which are our triglycerides. This occurs in the CYTOPLASM

4

What does fatty acid synthesis require

1. ATP
2. NADPH
3. acetlCoA carboxylase; our rate limiting step
4. Fatty acid synthase (large multisubunit complex)

5

Where do we get NADPH for FA synthesis

1. PPP pathway
2. malic enzyme -->converts malate directly to pyruvate and in so doing makes NADPH

6

What is the first step of palmitate synthesis

Synthesis of MalonylCoA; acetylCoA with CO2 stuck on end. Biotin associated attached with lysine. This makes malonylCoA. The synthesis of malonylCoA requires acetylCoA carboxylase, biotin and ATP

7

What is step 2

1. Malonyl CoA binds to acyl carrier protein
2. Acetyl group from acetyl CoA attaches to KS.

8

What are the 4 steps of elongation

1. Condensation: acetyl group transferred to malonyl group on ACP; CO2 is released
2. Reduction: NADPH is used to reduce aldehyde to alcohol
3. Dehydration: water is removed to form DB
4. Reduction: NADPH is used to reduce DB

9

What does malonyl acetyl transferase do

Takes 4 carbon unit from ACP and transfers it to KS; leaves ACP empty for new malonyl CoA to come in.

10

Which enzyme is responsible for condensation

KS

11

Which enzyme is responsible for reduction

KR

12

Which enzyme is responsible for dehydration

DH

13

Which enzyme is responsible for second reduction

ER

14

What is being produced in the first round of palmitate synthesis

4C acyl chain
-Then 6 more rounds that each add 2 C to make a total of 16
-Total of 7 rounds

15

What is overall being produced

7 malonylCoA
7 ATP
14 NADPH

16

Where does the conversion of palmitate to other FA's occur

smooth ER

17

What does elongation require in order to convert palmitate to other FA's

1. palmitoylCoA with no ACP and malonylCoA
2. NADPH
3. stearic acid

18

how many carbons in stearic fatty acid

18- no double bonds

19

what does desaturation require (prod DB)

oxygen, NADH and cytochrome b5, DB usually occurs at number 9 position

20

What is the rate limiting step

adding acetylCoA carboxylase

21

Most of acetyl CoA we make is in:

mitochondria; no mitochondrial transporters; so you have to convert them to citrate to make it go to cytoplasm for FA synthesis

22

How is citrate formed

oxaloacetate + acetyl CoA; citrate lyase converts it back to ^

23

What activates citrate lyase

insulin; its our fed hormone and we want to store energy as fat; so we convert it to tryglycerides and send it to adipose

24

Glucagon and ___inhibit process

epinephrine

25

How do you make glycerol - 3-phosphate

1. In liver, glycerol is taken up and adds ATP via glycerol kinase-->glycerol3phosphate
2. In adipose: goes through dihydroxyacetone phosphate and needs NADH to make glycerol-3-phosphate

26

what is precursor of triglycerides

glycerol 3 phosphate

27

Synthesis of triglycerides:
Triacylglycerol and Phosphatidic Acid

1. Long chain fatty acylCoA's are substrates to add FA's at carbon 1 and 2 via acyl-CoA synthetase. This requires ATP
2. Phosphatidic acid phosphatase removes phosphate; acyl transferase adds 3rd FA to form triacyglcerol; addition of each FA requires 2 high energy bonds

28

what are the broken down steps to make triacylglycerols

1.glucose + aa --> acetyl coA via activation of insulin to activate glycolysis
2. Acetyl cOA converts to malonyl CoA makes fatty acids
3. Fatty acids make triacylglycerols

29

What is lipoprotein lipase

activated by insulin; binds to lipoproteins and cleaves off lipids from triglyceride and releases glycerol back in to bloodstream which goes back to liver which can be made into glycerol 3 phosphate to make more triglycerides. Free FA come into adipose to combine with triacylcerols for storage

30

What are the different things that can be attached to polar head group of phospholipids

1. Serine
2. Ethanolamine
3. Choline
4. Glycerol
5. Inositol
6. cardiolipid

31

What are two strategies to attach head groups

1. Diacylglycerol activated with CDP and then stick on glycerol, inositol, or cardiolipin
2. Head group activated with CDP; ethanolamine or choline

32

Phosphatidylserine is made via ___exchange

base; with PE or PC

33

Phosphatidylcholine is made from

PE; which is made from CDP choline +DAG or methylation of PE

34

Phosphatdilethalamine is made from

CDP-ethanolamine +DAG

35

Sphingolipids have ___backbone

serine

36

PalmitoylCoA + serine=

sphingosine + CO2

37

Sphingosine + acetylCoA =

ceramide + CoA

38

Ceramide + PC=

sphingomyelin +DAG

39

Ceramide + UDP-glucose =

cerebroside +UDP

40

multiple sugars =

globoside; blood group antigens

41

Sphingosine are:

Serine backbone with palmitoyl CoA

42

Ceramide can convert to cerebroside or ____

sphingomyelin

43

What are four major stages of cholesterol synthesis

1. Condensation:3 Acetyl CoA to make mevalonate + CoA
2. Formation of activated isoprene: via mevalonate +3 ATP
3. Polymerization: squalene + 6 CO2
4. cyclization &transformation: end up with cholesterol

44

What makes ketone bodies

HMG CoA lyase

45

What is the committed step in cholesterol synthesis

HMG CoA reductase; activated by insulin, and blocked by glucagon.

46

What is found in fungal pathogens

Engosterol

47

Cholesterol head groups get masked so it becomes ____so it could get stored. They do this by forming ____

hyrophobic; esters

48

What does ACAT do

Enzyme to make cholesterol esters from cholesterol.

49

Prostaglandins and thromboxanes are made from an enzyme called:

prostaglandin endoperoxide synthase (COX)

50

What are the two catalytic activities of prostaglandin enderoperoxide synthase

1. cyclooxygenase
2. peroxidase

51

What are the end products of eicosinoids

1. Prostaglandins
2. Thromboxane
3. Leukotriene

52

What inhibits phospholipase A2

Cortisol

53

WHat is Cox1

Made all the time in most cells. Required for gastric tissue, renal homeostatsis, and platelet aggregation

54

What is Cox 2

Inducible in response to inflammation; PGs mediate pain, heat, redness, swelling of inflammation.

55

What inhibits both Cox1 and Cox2

Aspirin and indomethacin

56

What do Cox2 inhibitors cause

clots; production of thromboxane A2, and loss of production of PGI2

57

There are ___lipoxygenase inhibitors and leukotriene receptor antagonists are used to treat

5; asthma

58

what makes leukotrienes

lipoxygenase