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FA synthesis Flashcards

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1
Q

what are the two preparatory steps of FA synthesis

A

formation of malonyl CoA
binding of acetyl CoA and MalonylCoA to FAS1

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2
Q

what enzyme makes malonyl CoA

A

acetyl CoA carboxylase

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3
Q

what requires two forms of chemical energy

A

Biosynthesis of FA

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4
Q

how is citrate moved to the cytoplasm to make acetyl CoA

A

citrate transporter

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5
Q

how do we get from citrate to acetyl coa

A

citrate lyase transfers acetyl group to CoA

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6
Q

where is NADPH sources from for reduction reactions

A

PPP and malic enzyme

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7
Q

what does the second preparatory step lead to the release of

A

CoA

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8
Q

what do acetyl coa and malonyl coa connect to FAS via

A

thioester linkage

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9
Q

what adds acetyl CoA group onto SH group of ACP

A

MAT

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10
Q

where does MAT move acetyl coa to

A

SH group of ACP

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11
Q

what happens after acetyl coa is moved to ACP

A

it is transfered to SH group of KS

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12
Q

what happens after acetyl coa is moved to KS

A

MAT moves malonyl cao to SH of ACP

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13
Q

what is the last step in preparation for step 1 for FA synthesis

A

MAT moves malonyl cao to SH of ACP

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14
Q

what does ACP contain

A

4’-phosphopantetheine

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15
Q

what is 4’-phosphopentathiene

A

prosthetic group on ACP AND CoA that serves as a flexible arm, tethers FA chain to surface of FAS and carries reaction intermediates from one active site to the next

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16
Q

moving malonyl groups to SH group name

A

esterification

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17
Q

what form of acyl group is on KS

A

activated acyl group

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18
Q

what happens in the first condensation step of FA synthesis

A

activated acyl group and 2C from malonyl CoA undergo condensation to form a acetoacetyl ACP

CO2 leaves and the acyl chain is extended by 2 carbons

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19
Q

what is formed in the second step of FA synthesis- reduction

A

B keto product is reduced to an alcohol

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20
Q

what is the B keto product

A

acetoacetyl ACP

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21
Q

what catalyzes the reduction recation of FA synthesis

A

B ketoacyl-ACP reductase/ KR

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22
Q

what is required for the reduction step of FA synthesis

A

B ketoacyl-ACP reductase/ KR and NADPH as electron donor

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23
Q

what specifically happens to the carbons in the reduction step

A

reduction of carbonyl group at C3 to from D- B- hydroxybutyryl-ACP

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24
Q

what is the third step in FA synthesis

A

dehydration

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25
what enzyme catalyzes the third step in FA synthesis
B-hydroxyacyl-ACP dehydratase/ DH
26
what is formed by step 3 and how
trans-delta2-butenoyl-ACP by removing H20 elements from C2 and C3 of b-hydroxybutyryl-ACP
27
4th step of FA synthesis
reduction
28
what enzyme cataylyzes the 4th step
enoyl-ACP reductase/ ER
29
what does enoyl-ACP reductase/ ER do
catalyzes reduction of DB of trans delta2-butenoyl-ACP to form butyryl ACP
30
how do we set up for the next pass of FA synthesis
transfer of butyryl group from ACP to KS recharging ACP with new malonyl COa
31
where is C16 derived from
methyl carbon atom of the acetyl Coa used to initially prime the system
32
where is C15 derived from
carboxyl carbon atom of the acetyl Coa used to initially prime the system
33
what is 16:0 called
palmitate
34
how many cycles of FA (4 steps) does palmitate go throu
7
35
what releases palmitate
hydrolysis of thioester linkage by thioesterase/ TE
36
what does TE do
hydrolizes the thioester linkage
37
what regulates FA synthesis
ACC phosphorylation level of gene expression by AAC and FAS inhibition of FA synthesis and oxidation occuring together by malonyl CoA
38
how does malonyl coa inhibit futiile cycle
inhibits FA import into mitochondria to ultimately shut down B oxidation
39
what does ACC cause
polymerization into long inactive fillaments
40
what is the rate limiting step of FA synthesis
ACC phosphorylation
41
what is the precursor of long chain saturated FA
palmitate
42
FA elongatino systems lengthen...
palmitate
43
where does the lengthening of palmitate occur
in the smooth ER and mitochondria
44
what is the most common product of lengthening of palmitate occur
stearate 18:0
45
what enzyme is required for the desaturation fo FA
fatty acyl CoA desaturase
46
what does fatty acyl CoA desaturase do
catalyzes oxidative reaction indoducing double bond
47
what does desaturation of FA require
NADPH, cyt b5, and cyt b5 reductase
48
what accepts electrons in the desaturation of FA
O2 accepts 2 electrons from saturated FA and 2 electrons from cyt b5
49
what desaturases do humans have
4,5,6,9 but not beyond 9
50
what can desaturate positions beyond C9
plants
51
what are the essential FA
linoleate and a linolenate
52
what is linoleate
18:2 w-6
53
where are linoleate double bonds
9 and 12
54
a linolenate
18:3 w3
55
where are a linolenate duoble bonds
9,12,15
56
what do PUFAs do
help control membrane fluidity
57
where are cholesterols acrbon atoms provided by
acetate
58
what is essential intermediate for the pathway of cholesterol synthesis
isoprene units
59
what are the stages in cholestrol synthesis
condensation mevalonate to activated isoprene units polymerization of 6 isoprene units to form 30 carobn linear squalene cyclization of squalene to from 4 rings of steroid nucleus
60
what are two descriptive words for FA synthesis
endergonic and reductive
61
what is ACP recharged with after one round of FA synthesis
malonyl CoA
62
what is formed from the reduction step
D-B hydroxybutyryl- ACP
63
what does DH stands for
D-B hydroxyacyl ACP dehydratase
64
what is formed by the dehydratino step
trans delta2 butenoyl ACP
65
how many cycles of FA synthesis did palmitate go through
7
66
what activates and inactivates ACC
citrate activates it epinephrine phosphorylation and inactivation glucagon phosphorylation and inactivation high [AMP] phoshorylation and inactivation palmitoyl CoA inactivates it
67
what occurs in smooth ER and mitochondria
FA elongation systems
68
where do FA elongation systems happen
in mitochondria and smooth ER
69
what enzyme is used for FA desaturation
fatty acyl coa desaturase
70
what does FA coa desaturase require
NADPH, cytb5, cytb5 reductase
71
role of PUFAs
control membrane fluidity

metabolism (14 decks)

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