Fatty Acid and TAG Metabolism Flashcards Preview

Biochemistry Post Midterm > Fatty Acid and TAG Metabolism > Flashcards

Flashcards in Fatty Acid and TAG Metabolism Deck (52):
1

which two fatty acids cannot synthesize double bonds beyond the 9 Carbon position?

linoleic acid
alpha-linolenic acid

2

How must we obtain linoleic acid and alpha-linolenic acid?

from diet

3

what makes arachidonic acid?

linoleic acid

4

what is the parent of all eicosanoids?

arachidonic acid (from linoleic acid)

5

When is fatty acid synthesis and TAG synthesis most likely to occur?

during fed state

6

what hormone promotes TAG and fatty acid synthesis?

insulin

7

what is the prepretory step in fatty acid synthesis?

acetyl CoA is superactivated/prepped by making malonyl CoA

8

where are the enzymes of FA synthesis located?

cytoplasm

9

what does malic enzyme convert malate directly to?

pyruvate and removes CO2 and produces NADPH

10

what does acetyl CoA carboxylsae (ACC) need?

CO2 and biotin

11

what does citrate do the ACC?

activates allosterically (Short term)

12

what does palmitoyl CoA do to ACC?

allosterically inhibits ACC

13

what does phosphorylation on Ser/Thr residues through AMPK do to ACC?

inhibits ACC (hormonally)

14

what causes phosphorylation of ACC?

glucagon / epinepherine

15

when is ACC active?

dephosphorylated form

16

what does insulin activate to make ACC active?

protein phosphatase

17

FAS takes 1 malonyl CoA and adds how many carbons to it?

2

18

what are the two forms of FAS?

dimer (active)
monomer

19

how much energy is needed to synthesize FA?

7 ATP - to prep malonyl CoA
14 NADPHs - elongation steps

20

what determines the overall rate of FA synthesis?

availability of malonyl CoA

21

what energy source is important during elongation steps?

NADPH

22

Every 2 C added in FA synthesis are added in the form of what?

malonyl CoA - uses 2 out of the 3 C (1 C gets kicked off)

23

what are the 2 major roles of citrate?

allosteric activator of ACC
vehicle by which acetyl coA moves from mitochondria to cytoplasm

24

what moves acetyl CoA from mitochondria to cytoplasm?

citrate

25

where does chain elongation and desaturation occur?

ER

26

what 3 things do you need for the desaturation of FA?

1. desaturase
2.cytochrome B5
3. cytochrome B5 reductase + NADPH

27

what does elongation and desaturation allow us to do?

synthesize polysaturated FA from essentail FA

28

what stimulates TAG synthesis from FA?

insulin

29

what stimulates glycogen synthesis from glucose?

insulin

30

which part of TAGs is essential for its storage?

glycerol backbone

31

which tissues have glycerol phosphate?

adipose tissue
liver*

32

what are 90% of FA in plasmas as?

fatty acid esters (TAGS, cholsteryl esters, phospholipids) in circulating lipoproteins

33

where does unsaturated FA have double bonds?

3 C apart

34

what introduces the kinks to unsaturated FA?

cis

35

if linoleic acid is not supplied what becomes essential in diet?

arachidonic acid

36

what are the precursors of FA synthesis?

acetyl CoA (pantothenic acid)
ATP
NADPH
Co2

37

what is a key intermediate between fat and carb metabolism?

Acetyl CoA

38

what are the 3 pathways of FA synthesis?

1.synthesis of palmitate from Acetyl CoA
2.elongation of palmitate
3.desaturation

39

where is acetyl CoA in mitochondria coming from?

oxidation of pyruvate (PDH complex)

40

what does high ATP in the mitochondria inhibit?

isocitrate dehydrogenase

41

what is the first committed step of FA synthesis?

Acetyl CoA carboxylase (ACC)

42

what is the rate limiting enzyme for FA synthesis?

ACC

43

what does the carboxylation of acetyl CoA to form malonyl CoA require as far as energy?

1 ATP per malonyl CoA formed!

44

what are long term regulation of ACC that promote FA synthesis?

high carb and fat free diets - upregulation, induction

45

what are long term regulation of ACC that decrease FA synthesis?

high fat diets, fasting, glucagon - down reg, repression

46

what up regulates the amount of dimeric form of FAS expressed?

insulin

47

what are the key regulators of Acetyl CoA carboxylase (ACC)?

citrate
palmitoyl CoA/fatty acyl CoA
Insulin
Glucagon/Epinepherine

48

where does FA elongation occur by reversal of Beta oxidation?

mitochondria (minor elongation pathway)

49

where is the major elongation pathway taking place?

ER

50

what are sites of unsaturation introduced to?

fatty acyl CoA desaturases that introduce double bonds to 5,6,9 position

51

what are the essential FA?

linoleate
linolenate
*they have unsaturations beyond the 9 carbon

52

what does the synthesis of polyunsaturated FA start with?

linolenic acid