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Biochem Test II > Lipids III > Flashcards

Lipids III Flashcards

1
Q

In relation to the synthesis of phosphatidylcholine, what enzyme activates choline?

A

choline kinase

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2
Q

After activation, what is done to activated phospho-choline?

A

Phosphocholine is transferred to CTP

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3
Q

What enzyme transfers phosphocholine to CTP?

A

Phosphocholine cytidyltransferase

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4
Q

What enzyme transfers CDP-choline to DAG?

A

choline phosphotransferase

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5
Q

What is the alternative method of synthesizing phosphatidylcholine?

A

triple methylation of phosphatidylethanolamine

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6
Q

What is the first step in the synthesis of phosphatidylethanolamine?

A

Ethanolamine is activated by phosphorylation and then transferred to CTP

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7
Q

What is the function of ethanolamine phosphotransferase?

A

to transfer CDP-ethanolamine to diacylglycerol

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8
Q

What does ethanolamine phosphotransferase produce?

A

PE

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9
Q

What is the main enzyme responsible for the synthesis of phosphatidylserine ?

A

phosphatidylserine synthase

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10
Q

What is the function of phosphatidylserine synthase?

A

to replace the head group of PE with a serine

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11
Q

How does the synthesis of phosphatidylinositol differ from the other membrane phospholipids?

A

In PI, it is the DAG that is activated by binding to CTP

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12
Q

What is CDP-diacylglycerol formed from?

A

CTP and phosphatidic acid

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13
Q

Where is cardiolipin located?

A

Inner mitochondrial membrane

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14
Q

Essentially, what is cardiolipin?

A

A phosphatidic acid dimer connected by a glycerol bridge

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15
Q

What is the function of cardiolipin?

A

to aid in the folding of inner mitochondrial membrane electron transport complexes

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16
Q

What two diseases feature a decline in the level of cardiolipin?

A

Alzheimer’s and Parkinson’s

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17
Q

What is the outer leaflet of the plasma membrane rich with?

A

choline-containing lipids PC and sphingomyelin

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18
Q

What is the inner leaflet of the plasma membrane rich with?

A

PE and negatively charged lipids such as PS

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19
Q

What will happen to a cell with PS expressed on its outer surface?

A

destroyed by macrophages

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20
Q

What carbons on a TAG are acted on by which phospholipases?

A

C1 = PLA1

C2 = PLA2

C3 = PLC (removes phosphate group)

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21
Q

How are freshly synthesized phospholipids similar?

A

A saturated or oleic acid at C1 and an unsaturated FA at C2

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22
Q

What leaflet, inner or outer, is arachidonic acid contained?

A

inner

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23
Q

What fatty acid is arachidonic acid synthesized from? Why is this?

A

linoleic acid. Arachidonic has double bonds in the distal part of it and must be synthesized from an essential FA.

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24
Q

What phospholipase is responsible for cleaving arachidonic acid from its membrane lipid?

A

PLA2

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25
Q

What enzyme is responsible for incorporating arachidonic acid into its phospholipid?

A

phospholipase A2 acyltransferase

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26
Q

What are the three main functions of prostoglandins?

A
  1. vasodilation during inflammation
  2. uterine contractions
  3. inhibit platelet aggregation
27
Q

How do corticosteroids inhibit the production of prostaglandins?

A

directly inhibiting the function of PLA2

28
Q

What are leukotrienes synthesized from?

A

arachidonic acid

29
Q

What type of reaction stimulates leukotriene synthesis?

A

lipoxygenase

30
Q

What is the main function of LTC4 and LTD4?

A

to promote smooth muscle contraction in blood vessels, airways and the intestine

31
Q

What compounds make up the slow reacting substance of anaphylaxis (SRS-A)?

A

LTC4 and LTD4

32
Q

What type of (unusual) bond do plasmalogens possess?

A

fatty alcohol in an ether linkage

33
Q

How does plasmalogen synthesis begin?

A

With the transfer of an acyl group to the C1 of DHAP

34
Q

What is the 2nd, and arguably most important, step of plasmalogen synthesis?

A

The acyl group on C1 is then exchanged for a fatty alcohol

35
Q

What is the 3rd step of plasmalogen synthesis?

A

acyl group from acyl-CoA is transferred to the C2

36
Q

What is the final step in plasmalogen synthesis?

A

addidtion Choline (from CDP-choline) at C3

37
Q

In plasmalogen synthesis, where does the induction of the ether linkage take place?

A

peroxisomes

38
Q

What are sphingolipids derived from?

A

sphingosine

39
Q

What common phospholipid backbone do sphingolipids not contain?

A

glycerol

40
Q

In the first step of sphingolipid synthesis, what two molecules condense? What molecule is formed?

A

serine and palmitoyl-CoA.

Dihydrosphingosine

41
Q

What is the second step of sphingolipid synthesis?

A

attachment of an acyl group (often behenyl-CoA, C22) to the amino group of dihydrosphingosine

42
Q

What product is formed at the end of the 2nd step of sphingolipid synthesis?

A

dihydroceramide

43
Q

What reduction equivalent is given off when dihydroceramide is oxidized to ceramide?

A

FADH

44
Q

What is the function of ceramide regarding sphingolipid biosynthesis?

A

lipid backbone

45
Q

What must happen to ceramide to become a sphingolipid?

A

transfer of a head group to C1

46
Q

What does a transfer of a phosphocholine to C1 result with?

A

sphingomyelin

47
Q

What does a transfer of a glucose or galactose to C1 result with?

A

cerebroside

48
Q

What does transfer of a sulfate group to cerebrosides result in?

A

sulfatide

49
Q

What does the transfer of several neutral sugars to ceramide result with?

A

globosides

50
Q

What does the transfer of several sugars, one of which is NANA/sialic acid to ceramide result with?

A

gangliosides

51
Q

What is cardiolipin located?

A

inner mitochondrial membrane

52
Q

Essentially, what is cardiolipin?

A

two phosphatidic acids linked by a glycerol bridge

53
Q

What is the outer leaflet rich in?

A

choline containing lipids and sphingomyelin

54
Q

What is the inner leaflet rich in?

A

PS and PE

55
Q

stress induces what inner leaflet component to translocate to the outer leaflet?

A

PS

56
Q

How are freshly synthesized lipids similar?

A

saturated or oleic acid at C1

desaturated acid at C2

57
Q

What is arachidonic acid synthesized from?

A

linoleic acid

58
Q

What is the function of thromboxane synthase?

A

to produce thromboxanes from PGH2

59
Q

What are leukotrienes synthesized from?

A

arachidonic acid

60
Q

What type of reaction initiates leukotriene synthesis?

A

lipoxygenase

61
Q

What is the critical step in the synthesis of plasmalogens? Where does this occur?

A

ether linkage at C1.

Peroxisomes

62
Q

What are sphingolipids synthesized from?

A

Serine and palmitoyl-CoA

63
Q

The transfer of phosphocholine to ceramide yields what?

A

sphingomyelin

64
Q

Trasfer of glucose or galactose to ceremide yields what?

A

cerebroside

Biochem Test II (14 decks)

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