Fatty Acid Synthesis Flashcards Preview

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Flashcards in Fatty Acid Synthesis Deck (30)
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1
Q
Primary tissues for fatty acid synthesis
A
Liver*, kidney, brain, lung, mammary glands, adipose
2
Q
Where does fatty acid sythesis occur in the cell?
A
Cytosol
3
Q
What are fatty acids synthesised from?
A
acetyl-CoA
4
Q
What is the main source of acetyl-CoA?
A
Glucose
5
Q
Major enzymes in fatty acid synthesis
A
Acetyl-CoA carboxylase, Fatty Acid synthase
6
Q
From what is citrate formed?
A
Acetyl-CoA and OAA
7
Q
Citrate lyase
A
Cleaves citrate into Acetyl-CoA and OAA. Is only found in the cytosol.
8
Q
How is pyruvate formed from OAA in the cytosol?
A
Cytosolic malate DH forms malate, malic Ez forms pyruvate from malate
9
Q
Formation of Malonyl CoA
A
Acetyl CoA carboxylase uses CO2 and ATP to make Acetyl CoA into Malonyl CoA
10
Q
What activates acetyl CoA carboxylase?
A
Insulin (activates protein phosphatase)
11
Q
What stimulates AMPK?
A
AMP, AMPK covalant (via Glucagon or Epi). Inhibits aceytl-CoA Carboxylase
12
Q
Long-term "adative" regulation
A
Long high calories=increased synthesis of Acetyl CoA Carboxylase. Long low calorie=decreased synthesis of acetyl CoA carboxylase
13
Q
What are the starting and ending units of fatty acid synthase?
A
acetyl-CoA starts, 2 carbons added at a time, product is palmitate
14
Q
Acetyl transacylase
A
Adds acetyl group on #1 monomer
15
Q
Malonyl transacylase
A
Adds malonyl group on monomer #2
16
Q
3-ketoacyl synthase
A
Makes a 3-ketoacyl, causes decarboxylation, passes carbons from one monor to the other (back and forth)
17
Q
3-ketoacyl reductase
A
Reduces 3 ketoacyl to 2 hydroxy using NADPH
18
Q
Hydratase
A
Removes H2O to form a 2-enyol group
19
Q
Enoyl reductase
A
Saturates the CC double bonem uses NADPH, leaves a saturated acyl
20
Q
Thioesterase
A
Breaks off acyl group to leave palmitate
21
Q
Acyl-CoA synthase
A
converts palmitate to palmitoyl-CoA to allow further reactions
22
Q
What is a major source of NADPH?
A
pentose phosphate pathway
23
Q
Where does fatty acid elongation take place?
A
ER
24
Q
What are the preferred substrates and products of fatty acid elongation?
A
Palmitoyl-CoA is substrate. Product is stearoyl-CoA (18C)
25
Q
Why is elongation a separate process fron synthesis?
A
There are different enzymes doing the same process
26
Q
Formation of monosaturated fatty acids
A
in the ER. Stearoyl-CoA desaturase. Desaturation always occurs at C9. Product is oleoyl CoA* or palmitoleoyl-CoA (stearoyl is preferred).
27
Q
Functions of polyunsaturated fatty acids
A
increases membrane fluidity, source of eicosanoids
28
Q
What carbons can humans desaturate?
A
4,5,6, and 9. CANNOT desaturate Beyond* C9
29
Q
What are omega fatty acids?
A
Fatty acids counted from the furthest C, instead of the alpha carbon
30
Q
Why are omega 3 and 6 necessary for dietary intake?
A
Cannot synthesize past C9, so must be taken in via diet