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Biochem 2 > Exam 2 > Flashcards

Exam 2 Flashcards

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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
Other than the different enzymes and carriers, the process of elongation in the ER is identical to
Palmitate synthesis
26
Unsaturated fatty acids are formed by the action of
Fatty acyl-CoA desaturases
27
Types of mixed function oxidases
Desaturases
28
Mixed function oxidase
The enzyme oxidizes 2 different substrates simultaneously
29
___________ and ______________ share the same initial synthesis pathway that forms Glycerol-3-Phosphate
Triacylglycerols | Phospholipids
30
G-3-P
Glycerol-3-Phosphate
31
***Reaction 1 for forming G-3-P
NADH is used to reduce dihydroxyacetone phosphate to glycerol phosphate by the action of glycerol phosphate dehydrogenase
32
Reduces dihydroxyacetone phosphate to glycerol phosphate
NADH by the action of Glycerol Phosphate Dehydrogenase
33
***Reaction 2 for forming G-3-P
Glycerol is phosphorylated by glycerol kinase to form glycerol phosphate. ATP is the phosphate donor
34
Phosphorylates glycerol to form glycerol phosphate
Glycerol Kinase
35
2 acyl esters are added to the glycerol phosphate molecule by the action of
Acyl Transferase
36
After acyl transferase, fatty acids are converted to their active CoA thirster by
Acyl-CoA synthetase
37
Stearate (18:0) + HSCoA + ATP --->
Stearoyl-CoA + AMP + PPi
38
________________ is first formed, then ______________ is formed
1-Acylglycerol-3-phosphate | 1,2-Acylglycerol-3-phosphate
39
1,2-Acylglycerol-3-phosphate
Phosphatidic acid
40
Phosphatidic acid has a hydrogen head group and is the
Simplest Phospholipid
41
TAG Synthesis Step 1
Phosphatidic Acid + Phosphatidic Acid Phosphatase ---> Diacylglycerol (H20 goes in, Pi comes out)
42
TAG Synthesis Step 2
Diacylglycerol + Acyl Trasferase ---> Triacylglycerol | RCO-SCoA gois in, CoA-SH comes out
43
Glycerol to Phosphatidic Acid
COME BACK TO
44
2 major routes to form phospholipids
Strategy 1 and 2
45
Strategy 1
Diacylglycerol activated with CDP---> CDP-diacylglycerol --- (loss of CMP)--> Glycerophospholipid
46
Strategy 2
Head group activated with CDP ---> 1,2-Diacylglycerol ---(Loss of CMP)---> Glycerophospholipid
47
CTP:
CTP: PA Cytidylyl Transferase | Phosphatidic Acid ---(CTP in, PPi out)---> CDP-diacylglycerol
48
___________ contains a high energy bond between the phosphates and can act as a donor of ________ or as a donor of ______________
CDP-DAG DAG The phosphatidyl radical
49
How CDP-DAG is formed
Phosphatidic Acid ---(CTP:phosphate cytidylyl transferase in, PPi out)---> CDP-diacylglycerol
50
Decarboxylation of PS yields
PE
51
Condensation of 2 molecules of PG yields
Cardiolipin (diphosphatidyl-glycerol)
52
Phospholipid synthesis in E.Coli (bacteria) employs
strategy 1
53
Ps and PG are formed by
Strategy 1
54
Phosphatidic acid to Phosphatidylglycerol-3-phosphate
Phophatidic Acid --(CDP in, PPi out)---> CDP-diacylglycerol (+ PG 3-phosphate synthase) ---(Glycerol-3-phosphate in, CMP out)--> Phosphatidylglycerol-3-phosphate
55
Phosphatidic Acid to Phosphatidylserine
Phosphatidic Acid ---(CDP in, PPi out)--> CDP-Diacylglycerol (+ PS Synthase) ---(Serine in, CMP out)--> Phosphatidylserine
56
Glycerol-3-phosphate to Phosphatidylglycerol-3-phosphate
Glycerol-3-phosphate )+ PG-3-Phosphate Synthase) ---(loss of CMP)--> Phosphatidylglycerol-3-phosphate
57
In eukaryotes, anionic phospholipids (PG, DPG, Pi) are synthesized using
Strategy 1
58
CDP-DAG to Phosphatidylinositol
CDP-Diacylglycerol + PL Synthase ---(inositol in, CMP out)--> Phosphatidylinositol
59
In animals, PE and PC are made by
Strategy 2 | Ethanolamine and Cholin are activated as CDP-ethanolamine and CDP-choline
60
Ethanolamine to CDP-Ethanolamine
Ethanolamine (+ Ethanolamine Kinase) ---(ATP in, ADP out)--> Phosphoethanolamine (+ CDP-ethanolamine Cytidylyl Transferase) ---(CTP in, PPi out)--> CDP-ethanolamine
61
Choline to CDP-Choline
Choline (+ Choline Kinase) --(ATP in, ADP out)--> Phophocholine (+ CTP-choline cytidylyl transferase) ---(CTP in, PPi out)---> CDP-Choline
62
CDP-choline to Phosphotidylcholine
CDP-choline (+ CDP-choline diacylglycerol phoshpocholine transferase) ---(diacylglycerol in, 3'CMP ?? out)---> Phosphotidylcholine
63
Animals produce phosphatidyl serine by a process called
Headgroup exchange
64
Membranes fuse when
2 separate bilayers become one
65
Membrane Fusion
Primary means to change membrane composition and is a major mechanism involved in endocytosis and exocytosis
66
Membrane fusion MUST be ________ because__________
A highly regulated process | Fusion activity would randomly occur which in some instances would kill the cell
67
Fusion requires:
1) Close proximity of two membranes | 2) Reduced headgroup hydration
68
_____________ are primarily composed of PE and PS ideally in approximately a ______ ratio
Fusogenic membranes | 3:1
69
________ is the lease hydrated of the phospholipid headgroups
PE
70
PE can easily form
Hex II Phase | Hexagonal II
71
Inverted membrane head group facing fatty acid (outwards)
Hexagonal II
72
When membranes fuse, the PE and PS in the bilayers will ________ and fuse in the presence of ________
Destabilize | Ca 2+ (calcium)
73
PS is capable of
Tight Ca binding
74
When calcium binds to PS it ________ the net surface charge density and ___________ surface hydration repulsion
Reduces | Reduces
75
When calcium binds to PS is enhances ________________
Intermembrane van der Waals ATTRACTION
76
Various fusogenic proteins are involved in the process to
Help direct which bilayers come in contact and to help hold the bilayer close together
77
Fusogenic proteins help find
Involved membranes to come together
78
Virus Entry Into Host Cell (10 steps)
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
Can be removed from the membrane using buffers containing salts and/or buffers at extreme pH ranges
Peripheral membrane proteins
80
Extrinsic
Loose - Peripheral
81
Can only be removed with buffers containing detergents
Integral membran proteins
82
Intrinsic
Integral | Need bunch of hydrophobic amino acids
83
Bound to "anchor" protein
Peripheral | Succinate Dehydrogenase
84
Electrostatic Attraction
Peripheral | Myelin basic protein
85
Hydrophobic with little penetration
Peripheral | Pyruvate oxidase
86
Short terminal hydrophobic segment
Integral | Cytochrome 65
87
Single transmembrane Segment
Integral | Glycophorin
88
Multiple transmembrane segment
Integral Lactose Permease Number of hydrophobic section varies from protein to protein
89
Covalently linked lipid anchor
Integral | Alkaline Phosphatase
90
Isolation/Purification of Membrane Proteins: | In order to maintain the functionality of membrane proteins, you need to maintain the __________ in the buffer
Detergent
91
Hydropathy Plots
Attempt to predict membrane spanning alpha-helical regions from amino acid sequence
92
Transmembrane spanning regions are about __________ long and consist primarily of ___________
20 amino acids | Hydrophobic amino acids
93
Most commonly used hydropathy scale
Kyle and Doolittle
94
Kyle and Doolittle scale
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
2 examples of REALLY hydrophobic amino acids
Isoleucine and Leucine

Biochem 2 (3 decks)

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