Block 4 Nelson Questions Flashcards
(147 cards)
1
Q
How many protein coding genes in mitochondria?
A
13
2
Q
How many proteins in mitochondria?
A
About 683
3
Q
Permeability of Outer Mitochondrial Membrane
A
Porous to molecules smaller than 5 kDa
4
Q
Permeability of Inner Mitochondrial Membrane
A
Impermeable to ions, including protons
5
Q
Location of Cytochrome C
A
Intermembrane space
6
Q
State 3 Respiration
A
Active state when ADP added; Significant oxygen consumption
7
Q
State 4 Respiration
A
Resting State when ADP runs out; Low rate of oxygen consumption
8
Q
Mitochondrial morphology during resting state
A
Matrix space large; Intermembrane space small
9
Q
Mitochondrial morphology during active respiration state
A
Matrix space small; Intermembrane space large (pumped full of protons, water follows)
10
Q
Purpose of condensed cristae during Active (State 3) Respiration
A
Fusion may mediate rapid exchange of metabolites with cytosol
11
Q
Protein linked to Cristae morphology
A
Mitofilin (MINOS complex)
12
Q
Mitofilin
A
Linked to cristae morphology; Tubular junctions eliminated in knockdown, can’t export anything to cytosol
13
Q
What releases Cytochrome C
A
Signal from Bid, Bad, and/or Bax opens pores in outer membrane, releasing cytochrome C
14
Q
Action of Cytochrome C once released
A
Cytochrome C and Apaf1 recruit Caspase 9, forming Apoptosome
15
Q
Effect of apoptotic signal on morphology
A
Extensive fusion of cristae preceding Cytochrome C release
16
Q
Porin protein
A
Beta barrel protein that forms trimers in outer membrane of mito; allows small molecules (not proteins) to pass freely
17
Q
Protein:Lipid Ratio in Inner vs Outer Mitochondrial Membrane
A
3:1 inner, 1:1 outer
18
Q
Cardiolipin
A
Associated with many membrane complexes on inner mito membrane, essential for their proper function; 4 FA chains linked by Glycerol
19
Q
Barth Syndrome
A
Mutation in Cardiolipin synthesis gene; Results in defective mito, cardiomyopathy, muscle weakness
20
Q
Goal of Respiration
A
Reduce Oxygen to H20; Capture energy of electrons removed from Pyruvate
21
Q
Function of Superoxide Dismutase
A
Eliminates Superoxide (O2-) by converting it to H202; Deficient in Lou Gehrig’s
22
Q
What converts Superoxide to H2O2
A
Superoxide Dismutase
23
Q
Function of Catalase
A
Convert H2O2 to oxygen and water; Found in mitochondria; Also found in RBCs
24
Q
What converts H2O2 to oxygen and water
A
Catalase
25
What happens to H2O2 when Fe2+ is present?
Can react to form Hydroxyl Radical
26
What forms Hydroxyl Radical?
H2O2 reacting with Fe2+
27
What protects against Hydroxyl radicals
Vit C and E
28
Vit C and E
Protect against Hydroxyl Radicals
29
2 Functions of CAC
Electrons to ETC; Precursors for Biosynthesis
30
2 moeities on cytosolic side of Complex 3
Rieske Iron-Sulfur protein, Cytochrome C1
31
2 Regulatory components of PDH Complex
PDH Kinase and Phosphatase
32
3 Main Enzymes of PDH Complex
Pyruvate Decarboxylase E1, Dihdrolipoyl Transacetylase E2, Dihydrolipoyl Dehydrogenase E3
33
3 Postulates of Binding Change Mechanism
(1) Energy from H+ gradient used to release ATP; (2) 3 catalytic sites are each in unique conformation, conf's are interconvertible, rep the 3 stages of catalytic cycle (L -> T -> O); (3) Conf changes at 3 sties are driven by rotation of gamma sub relative to F1 ball
34
4 Steps that produce NADH in CAC
Pyruvate DH, Isocitrate DH, A-KG DH, Malate DH
35
5 Cofactors for PDH Complex
TPP, FAD, NAD, CoA, Lipoic Acid
36
5 Sources of Acetyl CoA
Pyruvate (Glycolysis); AA Degradation; FA B-oxidation; KBs; Ethanol Metabolism
37
Alpha and Beta Subunits of ATP Synthase
Form the "Ball" of F1; Only beta has catalytic activity
38
Antimycin
Binds to N center on matrix side of Complex 3 (prevents e's from reaching b hemes)
39
Aspartate/Malate Shuttle vs Glycerophosphate shuttle
NADH vs Ubiquinone Level
40
Branchpoint of Citrate in Mitochondria
(1) Can enter TCA Cycle; (2) exit through Citrate Shuttle to Export AcetylCoA for FA Synthesis; (3) Make alpha ketogluterate
41
CAC when Acetyl CoA high
Need for OAA; Pyruvate Decarboxylase stimulated (Pyruvate to OAA) and PDH inhibited; Shift from from oxidative to biosynthetic mode
42
Chemiosmotic Hypothesis
Inner membrane impermeable to H+, allowing gradient to be used for ATPase
43
Cofactor necessary for E1 Complex
Thiamin Pyrophosphate TPP (stabilize carbanion)
44
Cofactor necessary for E2 Complex
Lipoic Acid, Reacts w/ Carbanion intermediate from E1
45
Cofactor necessary for E3 Complex
?
46
Complex 2
Succinate DH; Tetramer; FAD and 3 Iron-Sulfur Clusters; Doesn't pump protons
47
Complex 4
Cytochrome C oxidase; reduces O2 to H20; Proton pump; Redox centers
48
Complex I
NADH DH; 7 subunits in mito genome; Membrane and Peripheral Arm
49
Defect in Mitofilin
No contacts b/t Cristae and bounding Inner Membrane; Can't export to Cytosol
50
Does FADH2 or NADH carry more energy?
NADH
51
E1 Reaction of PDH Complex
Decarboxylation of Pyruvate by E1; Produces unstable carbanion; Needs TPP
52
E2 Reaction of PDH Complex
Picks up Acetyl Group from TPP; Forms AcetylCoA
53
Elevator Model
Mutation of just 1 of 10-12 c subunits halts transport; Suggests subunit c rotates relative to a to form complete proton pathway
54
Energy made directly during TCA Cycle
1 GTP (Substrate-Level Phosphorylation)
55
Estimate for protons consumed per ATP synthesized
4
56
Fate of Pyruvate in TCA Cycle
Oxidized to 3 CO2 molecules
57
Findings of Noji experiment
Gamma subunit rotates
58
First place electrons go upon leaving cyt c
Copper A redox site of complex 4
59
First Ubiquinone binding site on Complex 3
Center P
60
Flavoproteins
Flavin gets electrons to pass to iron sulfur centers
61
Flow of electrons in Complex 2
Succinate -> FAD -> Iron-Sulfur Clusters -> Ubiquinone
62
FMN + AMP =
FAD
63
FMN in ETC
Cofactor bound to peripheral arm of Complex 1; Flavoprotein
64
How do electrons get to Complex 4
Cytochrome C carrier (one at a time)
65
How do oxygens reach active site of Complex 4?
Through lipid bilayer, not aqueous phase
66
How does Complex 4 compensate for adding electron to protein interior?
Take up a proton
67
How does structure change in Apoptotic Pathway
Extensive fusion of the Cristae precedes Cyt C release
68
How does the matrix appear in actively respirating mitochondria?
Condensed
69
How is NADH re-oxidized in aerobic conditions?
Passes electrons to ETC
70
How is NADH re-oxidized in anaerobic conditions?
Pyruvate is reduced to Lactate
71
How is Pyruvate imported into Mito Matrix?
Portin in Outer, Pyruvate Transport in Inner
72
How is the Intermembrane Space enlarged during Active Respiration?
Protons pumped in, and water follows
73
How many ATPs are made per complete revolute of gamma subunit relative to F1
3
74
How many e's are needed to reduce oxygen?
4
75
How many protons are pumped at each complex?
4 at Complex 1; 4 at Complex 3; 2 at Complex 4 (per pair of e's)
76
How many protons pumped per turn of Q cycle?
2
77
How many turns of Q cycle to fully reduce Ubiquinone?
2
78
How many turns of Q cycle to get 2 to Cytochrome C?
2, 1 per turn
79
How to Uncouple
Destroy proton gradient necessary for ox phosph (eg DNP)
80
Inhibitors of Isocitrate DH
ATP, NADH
81
Inhibitors of PDH Complex
Acetyl CoA, NADH, ATP (inhibitory phosphorylation)
82
Initial Reaction of PDH Complex
Decarboxylation of Pyruvate by E1; Produces unstable carbanion
83
Intermediate b/t NADH and Iron-Sulfur Center
Flavoprotein
84
Iron-Sulfer Clusters
Redox active centers that can accept and donate electrons; Conduit from FMN to Ubiquinone
85
Isocitrate Lyase
Cleaves isocitrate into Succinate and Glycoxylate
86
Main source of captured energy in TCA Cycle
NADH and FADH2
87
Malate Synthase
Adds Acetyl CoA to Glycoxylate to make Malate
88
Mito sn-Glycerophosphate DH
Part of Glycerophosphate shuttle for moving e's from Cytosolic NADH into ETC
89
Most important anapleurotic rxn of CAC?
Pyruvate Carboxylase: Pyruvate -> OAA
90
Only ETC Complex that doesn't pump protons
2, Succinate DH
91
Only membrane-bound enzyme in TCA cycle
Succinate Dehydrogenase
92
P/O Ratio
ATP Molecules produced per oxygen consumed, aka ATP produced/atom of oxygen
93
PEPCK
When OAA too high, coverts to PEP; uses one GTP
94
Problem with acetyl coA being precursor for FA biosynthesis
AcCoA made by PDH complex in mito, but FA synthesis occurs in cytosol
95
Purpose of E3 of PDH Complex
Removes electrons of sulfhydryls from Lipoic Acid; Forms NADH
96
Pyruvate Carboxylase
Pyruvate -> OAA; Can be used when not enough OAA for AcCoA
97
Pyruvate Dehydrogenase Action
Pyruvate to Acetyl CoA (irreversible)
98
Q Cycle
Ubiquinones at center P, one e to Rieske iron-sulfur and one to first b heme; e from Rieske to cytochrome c and e from heme to ubuiquinone at N center
99
Reaction mediated by Citrate Synthase
AcCoA + OAA -> Citrate (6C)
100
Redox centers of Complex 3
Two b type hemes in membrane subunit
101
Redox centers on Complex 4
2 Copper, 2 Hemes, Mg and Zn
102
Reduction Potentation of NADH/FADH2
Very high negative, tendency to move toward positive and release free energy
103
Role of Anconitase
Permits formation of A-KG
104
Rotenone Inhibitor
Binds to Complex 1 and Competes at Ubiquinone binding site (Electron transfer blocked)
105
Step that produces FADH2 in CAC
Succinate DH
106
Stigmatelin
Binds at P cener, the interface b/t iron-sulfur and cyt b (stops electron flow)
107
Stoichiometry of protons to electrons in ETC
4 protons/2 electonrs
108
T/F: The gamma subunit of ATP Synthase is symmetrical
False, different interactions with beta subunits around it
109
The addition of which enzyme joins the 2 halves of the CAC
A-KG Dehydrogenase
110
Two extra enzymes in Glycoxylate Cycle
Isocitrate Lyase and Malate Synthase
111
Ubiquinone
Lipid soluble e- carrier; Carries e's b/t complexes in ETC; Can accept one at a time, but can carry 2
112
Ubiquinone Binding Sites at Complex 1
1 Tightly Bound, 1 Loose (transfer from Complex 1 to 3)
113
UCP2 protein
Exist in adult human tissue, could be turned on to uncouple and waste energy
114
Uncoupling
ETC and Oxygen reduction work, but not ox phosph (removal of F1)
115
What are the 2 reactions that make the TCA Cycle
AcetylCoA + OAA -> A-KG (forward); OAA -> SuccinylCoA (reverse, heme)
116
What can block the transfer of electrons from Complex 1 to 3
Rotenone
117
What converts Pyruvate to Acetyl CoA
Pyruvate Dehydrogenase
118
What did famous reconstitution experiment show?
No intermediate, just protone gradient could power ATP synthesis
119
What do flavoproteins carry e's between?
Flavoproteins and Complex 3
120
What does Glycoxylation cycle bypass?
Decarboxylation steps of CAC
121
What does the Isocitrate Dehydrogenase enzyme produce?
Alpha-KG, CO2, NADH
122
What happens in too much OAA in CAC?
PEPCK converts it to PEP (costs one GTP)
123
What molecule from Glycolysis has to be imported into Mito Matrix for TCA?
Pyruvate
124
What parts still work when F1 part removed?
ETC and Oxygen reduction, but oxidative phosphorylation cannot
125
What prevents making sugar form fat in CAC?
Two decarboxylation steps; Acetyl CoA that enters is lost as CO2
126
What substrate in CAC is used for AA synthesis?
A-KG
127
What substrate in CAC is used for heme synthesis?
Succinyl CoA
128
Where does TCA cycle occur?
Mito Matrix
129
Which arm of Complex 1 contains all the redox active centers?
Peripheral
130
Which arm of Complex 1 contains the mito encoded subunits?
Membrane
131
Which Complex has channel for oxygen to reach active site?
Cytocrhome C Oxidase = Complex 4
132
Which complex has most mito coded subunits?
Complex 1
133
Which Complex hosts Q cycle
Complex 3
134
Which Complex of ETC contains Rieske Iron-Sulfur protein
Complex 3
135
Which complex reduces oxygen to water?
Complex 4 (cytochrome c oxidase)
136
Which E of PDH forms Acetyl CoA
E2
137
Which F is membrane part?
F_0
138
Which subunit forms the "axel" of F1
Gamma
139
Which subunit is identical b/t PDH and A-ketogluterate
E3
140
Which subunits form the rotor?
Subunit c, Epsilon, and Gamma
141
Which subunits form the stator?
a, b, alpha, beta, delta
142
Why do ETC complex proteins accept electons?
More positive reduction potential
143
Why is Succinate Dehydrogenase unusual in CAC?
Membrane bound and part of Complex 2
144
Why would A-KG leave the CAC?
AA synthesis, Glutamate
145
Why would OAA leave the CAC?
Aspartate
146
Why would we need to uncouple?
Allow electrons to flow in presence of high gradient
147
Yield from PDH Complex
1 Acetyl CoA and 1 NADH
