Chapter 26

Question 1

common intermediate in the synthesis of phospholipids and triglyceride

Answer 1

phosphatidate

Question 2

phosphatidate formed from ?

Answer 2

addition of two fatty acids to glycerol phosphate

Question 3

glycerol phosphate produced from ?

Answer 3

reduction of DHAP or phosphorylation of glycerol

Question 4

membrane lipids are synthesized here

Answer 4

on the cytosolic leaflet of the ER

Question 5

pathway from phosphatidate to TAG

Answer 5

phosphatidate >(lipid phosphate phosphohydrolase)> DAG >(DAG acyltransferase)> TAG

Question 6

TAG are primarily synthesized in ? and transported to ?

Answer 6

liver. adipose and muscle.

Question 7

triacylglycerol synthetase complex contains

Answer 7

lipid phosphate phosphohydrolase and DAG acyltransferase

Question 8

activation of phosphatidate or alcohol with ? is required to make phospholipids. Uses ? enzyme

Answer 8

CTP. phosphatidate cytidyltransferase

Question 9

phosphatidylinositol synthase reaction catalyzed

Answer 9

CDP-DAG + inositol&raquo_space; phosphatidylinositol + CMP

Question 10

synthesis of phospholipid starting with an alcohol

Answer 10

alcohol activated with CTP. Attached to DAG.

Question 11

most common phospholipid in animals

Answer 11

phosphatidylcholine

Question 12

phosphatidylcholine pathway

Answer 12

ethanolamine activated with CTP and attached to DAG. Addition of 3S-adenosylmethionine by liver methyltransferase

Question 13

sphingolipids are synthesized from ?

Answer 13

ceramide

Question 14

prominent lipid in the myelin sheath of nerve fibers

Answer 14

sphingomyelin

Question 15

ganglioside structures

Answer 15

ceramide with sugar chain

Question 16

in all sphingolipids, ? of ceramide is acylated

Answer 16

amino

Question 17

dipalmitoyl phosphatidylcholine is synthesized in the lung as a ?. Impaired synthesis results in ?

Answer 17

surfacant. respiratory distress syndrome.

Question 18

tay-sachs disease results from loss of ? involved in the degradation of ?

Answer 18

N-acetylhexoseaminadase. gangliosides

Question 19

carbons of cholesterol from acetyl CoA in 3 steps

Answer 19

1) synth of isopentyl pyrophosphate in cyto 2) condensation of 6 isopentyl-PP to form squalene in ER 3) cyclization of squalene and conversion to cholesterol in the ER

Question 20

? is a branch point in lipid metabolism

Answer 20

HMG-CoA

Question 21

HMG-CoA synthetase reaction catalyzed

Answer 21

acetoacetyl CoA + acetyl CoA&raquo_space; HMG-CoA

Question 22

site of most cholesterol biosynthesis

Answer 22

liver

Question 23

HMG-CoA reductase reaction (committed step in cholesterol synthesis)

Answer 23

HMG-CoA + 2NADPH&raquo_space; mevalonate

Question 24

HMG-CoA is an integral membrane protein of ?

Answer 24

ER

Question 25

? is the mitochondrial enzyme used in the production of ketone bodies

Answer 25

HMG-CoA lyase

Question 26

HMG-CoA lyase reaction catalyzed

Answer 26

HMG-CoA >> Acetyl-CoA + Acetoacetate (ketone bodies)

Question 27

mevalonate undergoes three rounds of phosphorylation to obtain ?

Answer 27

3-isopentyl pyrophosphate

Question 28

isopentyl PP isomerizes to ?

Answer 28

dimethylallyl PP

Question 29

synthesis of squalene

Answer 29

two C5 units (dimethylallyl PP and isopentyl PP) combine in head to tail condensation to give C10 unit. Additon of another isopentyl PP to give C15 unit. Two C15 units combine to form squalene.

Question 30

? activates squalene, then ? initiates converted ring closures to make lanosterol

Answer 30

squalene epoxidase. oxidosqualene cyclase.

Question 31

conversion of lanosterol to cholesterol

Answer 31

removes three methyl groups. reduction of one double bond. migration of one double bond.

Question 32

regulation of HMG-CoA reductase

Answer 32

low ATP reduces synthesis. inhibited by statin family.

Question 33

Activation of transcription of HMG CoA reductase mRNA

Answer 33

SREBP transcription factor is synthesized as membrane protein precursor. when cholesterol low, SREBP is released to bind to SRE to enhance transcription

Question 34

SCAP

Answer 34

SREBP cleavage activating protein

Question 35

statins are ? analogs

Answer 35

HMG

Question 36

cholesterol and TAGs are packaged into ? for transport between tissues

Answer 36

lipoprotein complexes

Question 37

delivery/"bad" forms of cholesterol

Answer 37

VLDL and LDL

Question 38

return/"good" form of choleserol

Answer 38

HDL

Question 39

HDL

Answer 39

sends cholesterol from dying cells and membranes undergoing turnover to liver for excretion

Question 40

LDL

Answer 40

main carrier of cholesterol in blood and regulate de novo synthesis

Question 41

healthy HDL:LDL ratio

Answer 41

3.5

Question 42

? mature into LDL

Answer 42

VLDL

Question 43

uptake of LDL particles via the LDL receptor is the paradigm for ?

Answer 43

receptor-mediated endocytosis

Question 44

excess cholesterol leads to ?

Answer 44

artherosclerosis

Question 45

management of high levels of cholesterol

Answer 45

statins reduce de novo synthesis. deduce dietary cholesterol. inhibition of cholesterol uptake by postively charged polymers (like cholestyramine)

Question 46

cholestyramine results in ?

Answer 46

excretion of bile acids requiring cells to synthesize new bile acids from cholesterol

Question 47

bile salts

Answer 47

polar derivatives of cholesterol that solubilize dietary lipids

Question 48

cholesterol is the precursor of ?

Answer 48

steroid hormones

Question 49

glucocorticoids

Answer 49

promote gluconeogenesis

Question 50

hydroxylations of cholesterol are performed by ?

Answer 50

cytochrome P450 monooxygenases

Question 51

?# of varieties of cytochrome P450 monooxygenases

Answer 51

57

Question 52

members of P450 monooxygenases are ? proteins

Answer 52

membrane associated hemes

Question 53

P450 monooxygenases reaction uses both ? and ?

Answer 53

oxygen and NADPH

Question 54

P450 monooxygenases mechanism

Answer 54

substrate binds. andrenodoxin reduces heme Fe. O2 binds. andrenodoxin reduces O2. Cleavage of O-O bond releases water. ROS abstracts H to create radical. radical grabs OH.

Question 55

P450 can also detoxify foreign substances by ?

Answer 55

increasing solubility

Question 56

7-dehrocholesterol is converted into ? by UV light

Answer 56

vitD

Question 57

vitamin D is converted to ? which regulates ?

Answer 57

calcitriol. regulates Ca++ uptake