Chapter 28

Question 1

what induces fatty acid synthesis?

Answer 1

insulin

Question 2

what inhibits fatty acid synthesis?

Answer 2

glucagon and epinephrine

Question 3

where does fatty acid synthesis occur?

Answer 3

in the cytoplasm

Question 4

what is the first stage of fatty acid synthesis?

Answer 4

the transfer if acetyl CoA out of the mitochondria into the cytoplasm

Question 5

what happens when citrate is transported into the cytoplasm?

Answer 5

it is cleaved into oxaloacetate

Question 6

what is the second stage of fatty acid synthesis?

Answer 6

activation of acetyl CoA to form malonyl CoA

Question 7

what is the third stage of fatty acid synthesis?

Answer 7

repetitive addition and reduction of two carbons units to synthesize C₁₆ fatty acid

Question 8

in the third stage of fatty acid, where does synthesize of C₁₆ fatty acid occur?

Answer 8

an acyl carrier protein, a molecular scaffold

Question 9

which step of fatty acid synthesis is the reverse of β - oxidation?

Answer 9

the third stage (repetitive addition and reduction of two carbons units to synthesize C₁₆ fatty acid)

Question 10

what does citrate do?

Answer 10

it carries acetyl groups from mitochondria to the cytoplasm

Question 11

where is citrate synthesized?

Answer 11

in the mitochondria

Question 12

what happens to citrate when it reaches the cytoplasm?

Answer 12

it is cleaved by ATP-citrate lyase to generate acetyl CoA for fatty acid synthesis

Question 13

what is generated from the cleavage of citrate in the cytoplasm?

Answer 13

acetyl CoA for fatty acid synthesis

Question 14

what is needed for fatty acid synthesis?

Answer 14

NADPH

Question 15

what is the committed step in fatty acid synthesis?

Answer 15

the formation of malonyl CoA

Question 16

what regulates the synthesis of fatty acids?

Answer 16

synthesis of malonyl CoA

Question 17

how is malonyl CoA synthesized?

Answer 17

by acetyl CoA carboxylase, an allosteric enzyme

Question 18

what enzyme catalyzes the formation of fatty acids?

Answer 18

fatty acid synthase

Question 19

where does fatty acid synthesis occur?

Answer 19

on the acyl carrier protein (ACP)

Question 20

what is the acyl carrier protein (ACP)?

Answer 20

a polypeptide linked to CoA

Question 21

what are the 4 steps of fatty acid synthesis?

Answer 21

1. condensation
2. reduction
3. dehydration
4. reduction

Question 22

fatty acid synthesis is always…

Answer 22

reducing

Question 23

how does fatty acid synthesis store energy?

Answer 23

in the form of electrons

every 2 carbons, electrons are added

Question 24

what sequence is repeated during fatty acid synthesis?

Answer 24

reduction, dehydration, reduction

Question 25

what is condensed during fatty acid synthesis?

Answer 25

malonyl CoA with butyryl ACP

Question 26

what are the limitations of fatty acid synthase?

Answer 26

fatty acid synthase cannot generate fatty acids longer than C₁₆ palmitate

Question 27

how do enzymes extend palmitate?

Answer 27

by adding two carbon units, using malonyl CoA as a substrate

Question 28

how are double bonds introduced into saturated fatty acids?

Answer 28

by enzymes bound to the endoplasmic reticulum

Question 29

what is the structure of arachidonate?

Answer 29

a 20-carbon fatty acid with four double bonds, derived from linoleate

Question 30

what is arachidonate?

Answer 30

a precursor for a variety of signal molecules 20 carbons long (eicosanoids)

Question 31

what does arachidonate leads to?

Answer 31

prostaglandins

Question 32

what are examples of local acting agents?

Answer 32

prostaglandins and other eicosanoids

Question 33

what do local acting agents do?

Answer 33

they are short-lived agents that alter activities of cells that synthesize them or are close by they bind membrane receptors

Question 34

what are the functions of prostaglandins and eicosanoids?

Answer 34

stimulate inflammation regulate blood flow to organs control ion transport across membranes modulate synaptic transmission and induce sleep

Question 35

in general, how is fatty acid synthesis regulation?

Answer 35

1. switched off by phosphorylation switched on by Dephosphorylation 2. allosterically stimulated by citrate 3. insulin stimulates 4. glucagon and epinephrine inhibit

Question 36

what is the committed/irreversible step of fatty acid synthesis?

Answer 36

conversion of Acetyl CoA to Malonyl CoA by Acetyl CoA Carboxylase 1

Question 37

what activates AMPK?

Answer 37

AMP Glucagon Epinephrine

Question 38

what inhibits AMPK?

Answer 38

ATP Insulin

Question 39

what does citrate do to carboxylase?

Answer 39

it partially activates it

Question 40

what inhibits carboxylase?

Answer 40

glucagon and epinephrine

Question 41

how do glucagon and epinephrine inhibit carboxylase?

Answer 41

by enhancing AMPK activity

Question 42

what stimulates carboxylase?

Answer 42

insulin

Question 43

how does insulin stimulate carboxyalase?

Answer 43

insulin stimulates the Dephosphorylation and activation of carboxylase

Question 44

what regulates the enzymes of fatty acid synthesis?

Answer 44

adaptive control

Question 45

what does the adaptive control of enzymes in fatty acid synthesis mean?

Answer 45

if adequate fats are not present in the diet, the synthesis of enzymes required for fatty acid synthesis is enhanced

Question 46

excess ethanol consumption

Question 47

what does the pathway for ethanol processing lead to?

Answer 47

excess production of NADH

Question 48

what does excess NADH result in?

Answer 48

inhibition of gluconeogenesis and fatty acid degradation enhancement of lactate production stimulation of fatty acid synthesis

Question 49

what does the inhibition of gluconeogenesis and enhancement of lactate production from excess NADH result in?

Answer 49

lactic acidosis

Question 50

what does the inhibition of Fatty acid degradation and stimulation of fatty acid synthesis result in?

Answer 50

accumulation of fats in the liver