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Biol 4890 > Chapter 26 > Flashcards

Chapter 26 Flashcards

1
Q

common intermediate in the synthesis of phospholipids and triglyceride

A

phosphatidate

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2
Q

phosphatidate formed from ?

A

addition of two fatty acids to glycerol phosphate

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3
Q

glycerol phosphate produced from ?

A

reduction of DHAP or phosphorylation of glycerol

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4
Q

membrane lipids are synthesized here

A

on the cytosolic leaflet of the ER

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5
Q

pathway from phosphatidate to TAG

A

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

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6
Q

TAG are primarily synthesized in ? and transported to ?

A

liver. adipose and muscle.

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7
Q

triacylglycerol synthetase complex contains

A

lipid phosphate phosphohydrolase and DAG acyltransferase

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8
Q

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

A

CTP. phosphatidate cytidyltransferase

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9
Q

phosphatidylinositol synthase reaction catalyzed

A

CDP-DAG + inositol&raquo_space; phosphatidylinositol + CMP

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10
Q

synthesis of phospholipid starting with an alcohol

A

alcohol activated with CTP. Attached to DAG.

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11
Q

most common phospholipid in animals

A

phosphatidylcholine

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12
Q

phosphatidylcholine pathway

A

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

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13
Q

sphingolipids are synthesized from ?

A

ceramide

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14
Q

prominent lipid in the myelin sheath of nerve fibers

A

sphingomyelin

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15
Q

ganglioside structures

A

ceramide with sugar chain

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16
Q

in all sphingolipids, ? of ceramide is acylated

A

amino

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17
Q

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

A

surfacant. respiratory distress syndrome.

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18
Q

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

A

N-acetylhexoseaminadase. gangliosides

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19
Q

carbons of cholesterol from acetyl CoA in 3 steps

A

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

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20
Q

? is a branch point in lipid metabolism

A

HMG-CoA

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21
Q

HMG-CoA synthetase reaction catalyzed

A

acetoacetyl CoA + acetyl CoA&raquo_space; HMG-CoA

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22
Q

site of most cholesterol biosynthesis

A

liver

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23
Q

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

A

HMG-CoA + 2NADPH&raquo_space; mevalonate

24
Q

HMG-CoA is an integral membrane protein of ?

A

ER

25
Q

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

A

HMG-CoA lyase

26
Q

HMG-CoA lyase reaction catalyzed

A

HMG-CoA&raquo_space; Acetyl-CoA + Acetoacetate (ketone bodies)

27
Q

mevalonate undergoes three rounds of phosphorylation to obtain ?

A

3-isopentyl pyrophosphate

28
Q

isopentyl PP isomerizes to ?

A

dimethylallyl PP

29
Q

synthesis of squalene

A

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.

30
Q

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

A

squalene epoxidase. oxidosqualene cyclase.

31
Q

conversion of lanosterol to cholesterol

A

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

32
Q

regulation of HMG-CoA reductase

A

low ATP reduces synthesis. inhibited by statin family.

33
Q

Activation of transcription of HMG CoA reductase mRNA

A

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

34
Q

SCAP

A

SREBP cleavage activating protein

35
Q

statins are ? analogs

A

HMG

36
Q

cholesterol and TAGs are packaged into ? for transport between tissues

A

lipoprotein complexes

37
Q

delivery/”bad” forms of cholesterol

A

VLDL and LDL

38
Q

return/”good” form of choleserol

A

HDL

39
Q

HDL

A

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

40
Q

LDL

A

main carrier of cholesterol in blood and regulate de novo synthesis

41
Q

healthy HDL:LDL ratio

A

3.5

42
Q

? mature into LDL

A

VLDL

43
Q

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

A

receptor-mediated endocytosis

44
Q

excess cholesterol leads to ?

A

artherosclerosis

45
Q

management of high levels of cholesterol

A

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

46
Q

cholestyramine results in ?

A

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

47
Q

bile salts

A

polar derivatives of cholesterol that solubilize dietary lipids

48
Q

cholesterol is the precursor of ?

A

steroid hormones

49
Q

glucocorticoids

A

promote gluconeogenesis

50
Q

hydroxylations of cholesterol are performed by ?

A

cytochrome P450 monooxygenases

51
Q

?# of varieties of cytochrome P450 monooxygenases

A

57

52
Q

members of P450 monooxygenases are ? proteins

A

membrane associated hemes

53
Q

P450 monooxygenases reaction uses both ? and ?

A

oxygen and NADPH

54
Q

P450 monooxygenases mechanism

A

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.

55
Q

P450 can also detoxify foreign substances by ?

A

increasing solubility

56
Q

7-dehrocholesterol is converted into ? by UV light

A

vitD

57
Q

vitamin D is converted to ? which regulates ?

A

calcitriol. regulates Ca++ uptake

Biol 4890 (16 decks)

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