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Biochem 2 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Synthesis of fatty acids takes place in

A

The cytosol (animals) and chloroplasts (plants)

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2
Q

The long carbon chains of fatty acids are assembled in a

A

repeating four step reaction sequence

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3
Q

The repeating four step reactions yield a ________________ which becomes the substrate for condensation with an activated ____________

A

Saturated acyl group

Malonyl group

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4
Q

The fatty acyl chain is lengthened by

A

2 carbons per cycle

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5
Q

When the acyl chain length reaches ____ carbons, the product that leaves the cycle is

A

16

The fatty acid Palmitic Acid 16:0

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6
Q

Carbons __ and ___ in the palmitate molecule are derived from the ______ and ________ carbon atoms of the acetyl-CoA that initially primed the cycle

A

15
16
Methyl
Carboxyl

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7
Q

All of the reactions of fatty acid synthesis are carried out by the multienzyme complex

A

Fatty Acid Synthase

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8
Q

Fatty acid synthase complex has

A

7 separate activities

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9
Q

Bacteria and Plants

A

7 activities and 7 separate polypeptides

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10
Q

Yeast

A

7 activities and 2 separate polypeptides

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11
Q

Vertebrates

A

7 activities and a SINGLE, large polypeptide

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12
Q

ACP

A

Acyl Carrier Protein

Carries acyl groups in thioester linkage

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13
Q

AT

A

Acetyl-CoA-ACP Transacetylase

Transfers acyl group from CoA to Cys residue of KS

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14
Q

KS

A

Beta-Ketoacyl-ACP Synthase
Condenses acyl and malonyl groups
(Has at least 3 isozymes)

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15
Q

MT

A

Malonyl-CoA-ACP Transferase

Transfers malonyl group from CoA to ACP

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16
Q

KR

A

Beta-ketoacyl-ACP reductase

Reduces beta-keto group to beta-hydroxyl group

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17
Q

HD

A

Beta-hydroxyacyl-ACP Dehydratase

Removes H2O from Beta-hydroxyacyl-ACP, creating double bond

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18
Q

ER

A

Enoyl-ACP Reductase

Reduces double bond, forming saturated acyl-ACP

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19
Q

Synthesis of Fatty Acid Sequence

A

1) Condensation (KS) (Loss of CO2)
2) Reduction of B-keto group (KR) (NADPH + H+ in and NADP+ out)
3) Dehydration (DH) (Loss of H2O)
4) Reduction of double bond (ER) (NADPH + H+ in and NADP+ out)
5) Translocation of butyryl group to Cys on B-ketoacyl-ACP-synthase (KS)
6) Recharging of ACP with another malonyl group (MAT)

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20
Q

They biosynthesis of fatty acids requires:

A

1) Acetyl-CoA
2) ATP
3) NADPH

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21
Q

Used to reduce the double bonds that are inserted in the growing acyl chain when malonyl-CoA condenses with Acetyl-CoA

A

NADPH

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22
Q

Serves as the precursor for the biosynthesis of long-chain saturated fatty acids in animal cells

A

Palmitic Acid

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23
Q

C-18, C-20, and longer fatty acids are formed by ______________ systems in the ________ and the __________

A

Fatty acid elongation
Smooth Endoplasmic Reticulum
Mitochondria

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24
Q

___________ is extended by 2 carbons to form _____________

A

Palmitoyl-CoA

Stearoyl-CoA

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25
Q

Other than the different enzymes and carriers, the process of elongation in the ER is identical to

A

Palmitate synthesis

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26
Q

Unsaturated fatty acids are formed by the action of

A

Fatty acyl-CoA desaturases

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27
Q

Types of mixed function oxidases

A

Desaturases

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28
Q

Mixed function oxidase

A

The enzyme oxidizes 2 different substrates simultaneously

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29
Q

___________ and ______________ share the same initial synthesis pathway that forms Glycerol-3-Phosphate

A

Triacylglycerols

Phospholipids

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30
Q

G-3-P

A

Glycerol-3-Phosphate

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31
Q

***Reaction 1 for forming G-3-P

A

NADH is used to reduce dihydroxyacetone phosphate to glycerol phosphate by the action of glycerol phosphate dehydrogenase

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32
Q

Reduces dihydroxyacetone phosphate to glycerol phosphate

A

NADH by the action of Glycerol Phosphate Dehydrogenase

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33
Q

***Reaction 2 for forming G-3-P

A

Glycerol is phosphorylated by glycerol kinase to form glycerol phosphate. ATP is the phosphate donor

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34
Q

Phosphorylates glycerol to form glycerol phosphate

A

Glycerol Kinase

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35
Q

2 acyl esters are added to the glycerol phosphate molecule by the action of

A

Acyl Transferase

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36
Q

After acyl transferase, fatty acids are converted to their active CoA thirster by

A

Acyl-CoA synthetase

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37
Q

Stearate (18:0) + HSCoA + ATP —>

A

Stearoyl-CoA + AMP + PPi

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38
Q

________________ is first formed, then ______________ is formed

A

1-Acylglycerol-3-phosphate

1,2-Acylglycerol-3-phosphate

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39
Q

1,2-Acylglycerol-3-phosphate

A

Phosphatidic acid

40
Q

Phosphatidic acid has a hydrogen head group and is the

A

Simplest Phospholipid

41
Q

TAG Synthesis Step 1

A

Phosphatidic Acid + Phosphatidic Acid Phosphatase —> Diacylglycerol
(H20 goes in, Pi comes out)

42
Q

TAG Synthesis Step 2

A

Diacylglycerol + Acyl Trasferase —> Triacylglycerol

RCO-SCoA gois in, CoA-SH comes out

43
Q

Glycerol to Phosphatidic Acid

A

COME BACK TO

44
Q

2 major routes to form phospholipids

A

Strategy 1 and 2

45
Q

Strategy 1

A

Diacylglycerol activated with CDP—> CDP-diacylglycerol — (loss of CMP)–> Glycerophospholipid

46
Q

Strategy 2

A

Head group activated with CDP —> 1,2-Diacylglycerol —(Loss of CMP)—> Glycerophospholipid

47
Q

CTP:

A

CTP: PA Cytidylyl Transferase

Phosphatidic Acid —(CTP in, PPi out)—> CDP-diacylglycerol

48
Q

___________ contains a high energy bond between the phosphates and can act as a donor of ________ or as a donor of ______________

A

CDP-DAG
DAG
The phosphatidyl radical

49
Q

How CDP-DAG is formed

A

Phosphatidic Acid —(CTP:phosphate cytidylyl transferase in, PPi out)—> CDP-diacylglycerol

50
Q

Decarboxylation of PS yields

A

PE

51
Q

Condensation of 2 molecules of PG yields

A

Cardiolipin (diphosphatidyl-glycerol)

52
Q

Phospholipid synthesis in E.Coli (bacteria) employs

A

strategy 1

53
Q

Ps and PG are formed by

A

Strategy 1

54
Q

Phosphatidic acid to Phosphatidylglycerol-3-phosphate

A

Phophatidic Acid –(CDP in, PPi out)—> CDP-diacylglycerol (+ PG 3-phosphate synthase) —(Glycerol-3-phosphate in, CMP out)–> Phosphatidylglycerol-3-phosphate

55
Q

Phosphatidic Acid to Phosphatidylserine

A

Phosphatidic Acid —(CDP in, PPi out)–> CDP-Diacylglycerol (+ PS Synthase) —(Serine in, CMP out)–> Phosphatidylserine

56
Q

Glycerol-3-phosphate to Phosphatidylglycerol-3-phosphate

A

Glycerol-3-phosphate )+ PG-3-Phosphate Synthase) —(loss of CMP)–> Phosphatidylglycerol-3-phosphate

57
Q

In eukaryotes, anionic phospholipids (PG, DPG, Pi) are synthesized using

A

Strategy 1

58
Q

CDP-DAG to Phosphatidylinositol

A

CDP-Diacylglycerol + PL Synthase —(inositol in, CMP out)–> Phosphatidylinositol

59
Q

In animals, PE and PC are made by

A

Strategy 2

Ethanolamine and Cholin are activated as CDP-ethanolamine and CDP-choline

60
Q

Ethanolamine to CDP-Ethanolamine

A

Ethanolamine (+ Ethanolamine Kinase) —(ATP in, ADP out)–> Phosphoethanolamine (+ CDP-ethanolamine Cytidylyl Transferase) —(CTP in, PPi out)–> CDP-ethanolamine

61
Q

Choline to CDP-Choline

A

Choline (+ Choline Kinase) –(ATP in, ADP out)–> Phophocholine (+ CTP-choline cytidylyl transferase) —(CTP in, PPi out)—> CDP-Choline

62
Q

CDP-choline to Phosphotidylcholine

A

CDP-choline (+ CDP-choline diacylglycerol phoshpocholine transferase) —(diacylglycerol in, 3’CMP ?? out)—> Phosphotidylcholine

63
Q

Animals produce phosphatidyl serine by a process called

A

Headgroup exchange

64
Q

Membranes fuse when

A

2 separate bilayers become one

65
Q

Membrane Fusion

A

Primary means to change membrane composition and is a major mechanism involved in endocytosis and exocytosis

66
Q

Membrane fusion MUST be ________ because__________

A

A highly regulated process

Fusion activity would randomly occur which in some instances would kill the cell

67
Q

Fusion requires:

A

1) Close proximity of two membranes

2) Reduced headgroup hydration

68
Q

_____________ are primarily composed of PE and PS ideally in approximately a ______ ratio

A

Fusogenic membranes

3:1

69
Q

________ is the lease hydrated of the phospholipid headgroups

A

PE

70
Q

PE can easily form

A

Hex II Phase

Hexagonal II

71
Q

Inverted membrane head group facing fatty acid (outwards)

A

Hexagonal II

72
Q

When membranes fuse, the PE and PS in the bilayers will ________ and fuse in the presence of ________

A

Destabilize

Ca 2+ (calcium)

73
Q

PS is capable of

A

Tight Ca binding

74
Q

When calcium binds to PS it ________ the net surface charge density and ___________ surface hydration repulsion

A

Reduces

Reduces

75
Q

When calcium binds to PS is enhances ________________

A

Intermembrane van der Waals ATTRACTION

76
Q

Various fusogenic proteins are involved in the process to

A

Help direct which bilayers come in contact and to help hold the bilayer close together

77
Q

Fusogenic proteins help find

A

Involved membranes to come together

78
Q

Virus Entry Into Host Cell (10 steps)

A

1) Binding to sialic acid receptors
2) Triggers endocytosis
3) HA (hemogglutination) peptide folded at pH 7
4) Reduced pH in endosome causes conformation change
5) HA fusion peptides extend into endosomal membrane
6) HA undergoes confromation change to form hairpin
7) Viral envelope and endosomal membrane pulled together
8) HA creates distortion/disruption of bilayer
9) Outer leaflet of virus fuses with inner leaflet of endosome
10) viral contents enter cytoplasm

79
Q

Can be removed from the membrane using buffers containing salts and/or buffers at extreme pH ranges

A

Peripheral membrane proteins

80
Q

Extrinsic

A

Loose - Peripheral

81
Q

Can only be removed with buffers containing detergents

A

Integral membran proteins

82
Q

Intrinsic

A

Integral

Need bunch of hydrophobic amino acids

83
Q

Bound to “anchor” protein

A

Peripheral

Succinate Dehydrogenase

84
Q

Electrostatic Attraction

A

Peripheral

Myelin basic protein

85
Q

Hydrophobic with little penetration

A

Peripheral

Pyruvate oxidase

86
Q

Short terminal hydrophobic segment

A

Integral

Cytochrome 65

87
Q

Single transmembrane Segment

A

Integral

Glycophorin

88
Q

Multiple transmembrane segment

A

Integral
Lactose Permease
Number of hydrophobic section varies from protein to protein

89
Q

Covalently linked lipid anchor

A

Integral

Alkaline Phosphatase

90
Q

Isolation/Purification of Membrane Proteins:

In order to maintain the functionality of membrane proteins, you need to maintain the __________ in the buffer

A

Detergent

91
Q

Hydropathy Plots

A

Attempt to predict membrane spanning alpha-helical regions from amino acid sequence

92
Q

Transmembrane spanning regions are about __________ long and consist primarily of ___________

A

20 amino acids

Hydrophobic amino acids

93
Q

Most commonly used hydropathy scale

A

Kyle and Doolittle

94
Q

Kyle and Doolittle scale

A

Uses hydropathy of amino acids as measured by the hydration potential. The frequency residues are found in globular water-soluble proteins and amino acid relative polarity

95
Q

2 examples of REALLY hydrophobic amino acids

A

Isoleucine and Leucine

Biochem 2 (3 decks)

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