intro to FA synthesis

Question 1

where does the majority of FA come from

Answer 1

diet

Question 2

what do we do with exess protein or carb

Answer 2

convert to FA and store them

Question 3

where does FA synthesis occur

Answer 3

in liver, adipose tissue, lactating mammary glands

Question 4

where does FA biosynthesis take place

Answer 4

in the cytoplasm

Question 5

what facilitates the elongation of FA chain

Answer 5

FAS 1

Question 6

what is required for carboxylation steps of FA synthesis

Answer 6

ATP

Question 7

what powers reduction steps in FA synthesis

Answer 7

NADPH

Question 8

in what kind of organism does FA synthesis and breakdown occur in different cellular compartments

Answer 8

in eukarytoes

Question 9

where does FA breakdown occur

Answer 9

mitochondria

Question 10

where does FA synthesis occur

Answer 10

cytosol

Question 11

what is catalyzed by different sets of enxymes

Answer 11

FA breakdown and biosynthesis

Question 12

what are the starting materials for FA biosynthesis

Answer 12

malonyl CoA and acetyl CoA

Question 13

commitment, rate limiting, and regulation step- what enzyme does ths

Answer 13

Acetyl CoA carboxylase

Question 14

what catalyzse the irreversible formation of malonylcoa from acetyl coa

Answer 14

Acetyl CoA carboxylase

Question 15

what prosthetic group does Acetyl CoA carboxylase contain

Answer 15

biotin- Vit B7

Question 16

what does Acetyl CoA carboxylase do

Answer 16

transfers carboxyl group from HCO3/ bicarbonate to biotin in ATP dependant reaction

Question 17

what does Acetyl CoA carboxylase need to work

Answer 17

ATP

Question 18

what happens after transfers carboxyl group from HCO3/ bicarbonate to biotin in ATP dependant reaction

Answer 18

carboxyl group is carried by biotin to different active site where CO2 is transferred to acetyl CoA to yiled malonyl coA

Question 19

what is acetyl coa brought into the cytoplasm as

Answer 19

citrate

Question 20

what is the purpose of making malonyl CoA

Answer 20

to make subsequent steps more thermodynamically favourable

Question 21

what domain does carboxyl group add onto biotin

Answer 21

in the biotin carboxylase domain

Question 22

what initially attatches the growing FA chain to the enzyme

Answer 22

thioester linkage via 2 thiol groups

Question 23

how many enzymes catalyze each cycle to FA synthesis

Answer 23

4

Question 24

what are the four steps of FA synthesis

Answer 24

1. condensation of growing chain with activates acetate
2. reduction of cabonyl to hydroxyl
   3.dehydration of alcohol to trans alkene
3. reduction of alkene to alkane

Question 25

what do the reduction steps do with respect to electron carriers

Answer 25

use elentrols from NADPH + H and make NADP+`

Question 26

by how many carbons does each subsequent elongation step increase the length of FA by

Answer 26

2

Question 27

when does FA synthesis stop

Answer 27

at 16 carbons

Question 28

FAS 1 polypeptide structure

Answer 28

single polypeptide chain which contains 7 catalytic site each with differnt function

Question 29

homodimer function in FAS1

Answer 29

each function independantly

Question 30

where is ACP

Answer 30

domain in FAS1

Question 31

what shuttles acyl group from one active site to another in sequence- covalently linked to acyl group

Answer 31

ACP

Question 32

what is vit B5 derivative attatched to

Answer 32

ACP

Question 33

what does vit B5 derivative contain

Answer 33

SH group that allows for attatchement to acetyl coa to donate atoms to growing chain

Question 34

Preparatory Step in FA biosynthesis

Answer 34

Acetyl CoA and malonyl CoA (or longer fatty acyl chain in later steps) are bound to FAS I – CoA portions are lost – bind via thioester terminus of the FAS I on ACP