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Flashcards in Lipid synthesis Deck (58)
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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