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Flashcards in Lipogenesis Deck (26):
1

Fatty acid synthesis occurs mainly in the?

Liver and adipose tissue

2

3 steps of FA synthesis

1)Cytosolic entry of Acetyl CoA (Citrate
2) Malonyl CoA (RLS)
3) FA chain formation

3

What enzyme converts citrate to oxaloacetate and results in Acetyl CoA in the cytosol?

ATP Citrate Lyase.

4

Acetyl CoA -> Malonyl CoA

Acetyl CoA carboxylase (RLS) needs Biotin and CO2 requires ATP

5

hOW IS mALONYL cOa A REGULATOR

It inhibits Carnitine acyltransferase which is the RLS of degradation

6

Malonyl Coa -> Palmitate

Fatty acid synthase. promoted by Insulin, glucocorticoid hormones, inhited PUFA

7

FAS

Condensation, Reduction, Dehyration, reduction

8

What are the 2 sources of NADPH

Malic enzyme and PPP

9

Where are FA elongated passed 16 C long?

Smooth ER, lengthens 2 C at a time using NADPH, use Malonyl CoA,

10

What carbon donors does SER and Mitchochondria use?

SER: malonyl CoA
mitochondria: acetyl CoA

11

Humans have 4 desaturases, where are they?

4, 5, 6, 9

12

Where and how does desaturation occur?

in SER, use NADPH, O2, catalyzed by Acyl CoA Desaturases. Humans cannot synthesize double bond beyond C 9 and 10

13

Regulation of Desaturases

Induced by Insulin, Suppressed by dietary PUFAs, Dietary cholesterol induces carbon 9 desaturation only

14

Essential FA

Linoleic acid (18:2 w 6) used to make arachidonic acid
Linolenic acid used to make EPA and DHA

15

Which FA can diffuse into mitochondria and which need to be actively transported?

Diffuse: SCFA, MCFA

ACTIVE (Carnitine Shuttle): LCFA, VLCFA

16

What are the enzymes in the Carnitine Shuttle?

1) Fatty acyl CoA Synthetase
2) CPT-1 or Carnitine acyltransferase (RLS) inhibited by Malonyl CoA
3) Carnitine-acylcarnitine translocase- (CACT)
- Antiporter: FA-carnitine in and carnitine out, moves FA-carnitine into intermembrane space
4) CPT-2: Adds CoA, and releases Carnitine

17

What are the 4 steps of B Oxidation

1) Oxidation: Acyl CoA Dehydrogenase:synth FADH2
2) Hydration
3) Oxidation: NADH
4) Thiolysis: Acetyl CoA

18

MCAD (medium chain Acyl CoA dehydrogenase

most diseases and defects associated with MCAD

19

4 enzymes in B Oxidation

1) Acyl CoA dehydrogenase
2) Hydratase
3) Dehydrogenase
4) acyl tranferase or ketothiolase

20

What happens with odd number C fatty acids?

1)Becomes Propionyl CoA uses propionyl CoA carboxylase (requires biotin then goes to methylmalonyl CoA
which uses methylmalonyl CoA mutase to go to succinyl CoA which enters TCA cycle

21

What do you do for B oxidation of unsaturated FA's?

1) Reductases and Isomerases

22

What about VLCFA'S >20?

Oxidized in the peroxisome. does not produce ATP, produces H2O2

23

Some key differences in Peroxisomal B-Oxidation and normal

1) 1st step catalyzed by acyl-CoA oxidase

24

MCAD Deficiency side effects

impairs breakdown of MCFA's, secondary carnitine deficiency, C8 FA builds up in liver, toxic, interferes with urea cycle, Increased urea levels, patient depends on glucose for energy

25

Where are Ketone bodies synthesized?

Only in the liver.

26

How are they synthesized?

Acetoacetate, acetone, B hydroxy butyrate