Lecture 2 Flashcards
1
Q
pH
A
Concentration of protons in a particular medium
2
Q
Primary role of adipose tissue in short circuiting the chemiosmotic proton circuit
A
Thermogenesis (production of heat)
3
Q
Another name for potential difference
A
Protonmotive force
4
Q
___ resembles a proton circuit
A
Electrical circuit
5
Q
Electrical and proton circuits have a power source capable of moving electrons from __ to __
A
Cathode to anode (+ to -)
6
Q
How are electrical and proton circuits ruled by the same forces
A
There is a potential gradient that could be generated
7
Q
What is the potential gradient measured as in the mitochondria
A
Membrane potential
8
Q
Membrane potential
A
Potential of the membrane to do work
9
Q
Unit of potential difference
A
Volts/milivolts
10
Q
Unit of current
A
Amps
11
Q
Factors derived from potential difference and current
A
Energy transmission and resistance to components in a circuit
12
Q
Unit of energy transmission
A
Watts
13
Q
Unit of resistance of components in the circuit
A
Ohms
14
Q
Which circuit is more complex: proton or electrical
A
Proton
15
Q
Proton circuit resembles an electrical circuit with multiple ___
A
Batteries
16
Q
Open circuit example
A
Battery is not connected to the appliance
17
Q
What type of circuit is needed to perform useful work
A
Closed
18
Q
Why is a closed circuit needed to perform useful work
A
Protons need to be channeled back
19
Q
Factors that make the mitochondrial circuit complex
A
Multiple enzymes capable of pumping protons across the membrane, multiple batteries
20
Q
Mitochondrial circuit battery layout
A
Parallel
21
Q
Why do mitochondrial circuits have batteries arranged in parallel
A
Amplifies the ability of the battery top operate at a higher current
22
Q
Voltage with batteries in parallel
A
Same voltage
23
Q
Moving ___ of __ is all you need to generate pmf
A
1 nano mole of H+
24
Q
___ is not directly capable of performing useful work
A
Open circuit
25
Does an open circuit have an electrical potential
Yes
26
Is there proton flow across the inner membrane back to the matrix in open circuit
No
27
What happens because there is no proton flow across the inner membrane in an open circuit
Protons will accumulate in the intermembrane space
28
Affect on pH when protons accumulate
pH can drop by 0.5
29
Redox potential
Potential of reduction and oxidation reactions occurring across the TCA cycle
30
__ are capable of being oxidized by proton pumps
Reducing agents
31
Potential of redox reactions will equal the ___
Electrical potential across the membrane
32
Redox potential balances ___
The electrical potential
33
Which circuit has the highest pmf
Open circuit
34
Why is the potential the highest in open circuit
The gradient is large
35
In which circuit is ATPase activated
Closed circuit
36
What does activation of ATPase lead to
Protons flow back into the matrix
37
In the closed circuit, pmf is slightly ___ than in open circuit
Lower
38
Can the closed circuit perform useful work with a lower pmf
Yes
39
Closed circuit is the equivalent of an electrical circuit being switched on/off
On
40
Which circuit describes the thermogenic function of BAT
Closed but shorted circuit
41
How does BAT short the circuit
Enzyme mediated (NOT with protonophores)
42
A closed but shorted circuit affects the amount of ___ and __ utilized
Reducing agents and O2
43
___ induce movement of protons across the membrane uncoupled from ATP production
Protonophores
44
How do protonophores induce movement of protons across the membrane uncoupled from ATP production
Poke holes in the inner membrane so H+ protons can flow
45
Pmf in the closed but shorted circuit
Slightly lower
46
Why is the pmf slightly lower in the closed but shorted circuit
Because protonophore tries to dissipate the gradient
47
Which circuit has the maximal electron flow
Closed but shorted circuit
48
Effect of fast electron flow in the closed but shorted circuit
Electron acceptor (oxygen) is used at a faster rate
49
Respiration of mitochondria in closed but shorted circuit
Maximal capacity
50
The electron transport system is strictly dependent on ___ derived from the ___
Substrates derived from the TCA
51
Another name for the TCA
Citric acid/krebs cycle
52
Substrates from the TCA cycle that fuel the pumping of protons across the inner membrane
Reducing agents
53
Redox potential is high when ___
Substrates are available
54
How can pmf be dissipated
Coupled or uncoupled to ATP synthesis
55
___ play an important role in redox reactions
Reducing agents
56
NADH donates electrons into ___
Complex I
57
Complex II
Succinate dehydrogenase
58
What does succinate produce
FADH2
59
FADH2 donates electrons into
Succinate dehydrogenase
60
Succinate dehydrogenase translocates electrons to____
Ubiquital Q pool
61
Mitochondrial dysfunction and associated diseases are usually tied to ___
Enzyme complexes and their functioning
62
Why is pmf measured
To assess metabolic function
63
Parameters that need to be evaluated to measure pmf
- Electrical potential across a membrane
| - Proton gradient across a membrane
64
Symbol for electrical potential across a membrane
delta ceptar
65
Symbol for proton gradient across a membrane
delta pH
66
What part is usually negative
Matrix
67
What part is usually positive
Intermembrane
68
Ion that contributes to overall positive charge in the intermembrane space besides H+
K+
69
Per every 1 nanomole moved across the membrane, monovalent ions increase ___ fold every __ mV
10-fold every 60mV
70
Electrical potential of a membrane
60 mV
71
Measure of membrane potential is based on the charge inside/outside of the membrane
Inside
72
Many techniques of measuring pmf have been developed since ___
1969
73
Methods of measuring pmf
- Ion specific electrodes to measure delta ceptar (electrical potential)
- Radioisotope technique
- Optical indicators of delta ceptar (electrical potential)
74
Ion specific electrode method dates back to ___
1969
75
Why is ion selection crucial in ion specific electrode method
- Must have the right charge
- Must achieve electrochemical equilibrium rapidly
- Needs to move across membrane by a single mechanism
- Cannot be metabolized
76
What charge must ions have in the ion specific electrode method
Cation (positive)
77
To move across the membrane rapidly, the selected ion must be __ in nature
Hydrophobic
78
Mechanisms of moving ions across the membrane
Protein-mediated and bilayer-mediated
79
Why cant the selected ion be metabolized
You do not want the indicator to be used up
80
Most commonly used ions in the ion specific electrode method
TPP+ and TPMP+
81
Group that both TPP+ and TPMP+ have
Phosphonium group
82
Phosphonium is hidden by ____
Hydrophobic groups
83
In the ion specific electrode method, ions are coupled to
Electrodes
84
In electrodes, anoids and cathoids are separated by ___
Salt solution
85
TPP+ and TPMP+ are accumulated and quantified in ___
Intermembrane space
86
TPP+ and TPMP+ ___ over time
Decrease
87
TPP+ and TPMP+ move across the membrane into the ___
Matrix
88
Changes in the concentrations of ___ can be used to calculate pmf
Cations
89
In order to calculate the pmf, there has to be a way to calculate the __ of the matrix
Volume
90
Radioisotope technique is modified from ___
Ion-selective assay
91
Radioisotopes used in radioisotope technique
Rubidium and 3H
92
What is 3H
Hydrogen with 3 protons
93
3H is used in the formation of ___ in the electron transport system
Water
94
___ is used as a control in the radioisotope technique
14C sucrose in pellet (sucrose labeled with C14)
95
Sucrose is a ___
Carbohydrate
96
Is sucrose permeable to the phospholipid bilayer
No
97
How can you get a sucrose pellet
After centrifugation of cells with mitochondria in incubation medium and silicone oil
98
Mitochondria are incubated with ___
Radioisotopic compounds
99
What equation is used in the radioisotope technique
Nernst equation
100
Nernst equation
Equilibrium equation
101
What is used in the radioisotope technique
Nernst equation and space used by the radio-labeled sucrose, TPP+, and H+ in the pellet
102
Radiolabeled water in the Nernst equation
Vh
103
What is the Nernst equation used to estimate
The overall volume of the matrix and membrane potential
104
How are optical indicators of delta ceptar used
To evaluate changes in the membrane potential associated with pmf
105
Mitchell estimated membrane potentials of about ___ in an open circuit
200 mV
106
A membrane potential of 200 mV results in an electrical potential of _____
300,000 volts per cm
107
___ can alter the orientation/shape of specialized components within the membrane
Strong electrical fields
108
What is the result of altered orientation/shape of specialized components within the membrane
Change of spectral properties
109
Membrane bound components that can change with strong electrical fields
Carotenoids in chloroplasts and lipophilic ions on mitochondria
110
Example of lipophilic ion
TMRM+
111
How to observe spectral properties
Apply dual wavelength spectrophotometers
112
Dual wavelengths for lipophilic ions
Lambda 1 and 2
113
Different wavelengths are observed in different ___
Respiratory states
114
More mitochondria = ___ flourescence ratio
Higher
115
More ADP = ___ membrane potential
Decreased
116
Addition of FCCP = ___ membrane potential
Decreased
117
Why is there decreased membrane potential with the addition of FCCP
pmf is low because it cannot retain protons on one side of the membrane
118
Every time there is a change in the membrane potential, there is a change in the ___ between the two wavelengths
Flourescence ratio
119
___ can be used as an indicator of membrane potential
Flourescense ratio
120
Respiratory state
Refers to oxygen consumption in a specific scenario
121
Other ___ can move across the inner membrane and affect the controllers of pmf
Charged particles
122
Forces can either ___ or ___ pmf
Dissipate or generate
123
___ and ___ can be used to calculate pmf
delta pH and membrane potential
124
Deenergized mitochondria
Pumps not fueled by substrates
125
pmf in deenergized mitochondria
0
126
Membrane potential in deenergized mitochondria
0 (no electrical potential)
127
Delta pH in deenergized mitochondria
0 (the pH is not 0, but the change in pH is > no net pumping of protons to alter pH)
128
What ions balance charges
Other cations (mostly K+)
129
1 nanomole of H+ pumped results in a delta ceptar of
200 mV
130
Ion permeant reduces __ and __, which is compensated by increased ___
delta ceptar
pmf
delta pH
131
Uptake of ___ in response to high pH dissapates the pH gradient, restoring ___ but inducing mitochondrial swelling
Weak acids
| delta ceptar
132
Reducing agents generate a ___
Gradient
133
___ change in pH when reducing agents are added
Very low
134
Matrix is made more ___ when reducing agents are added
Negative
135
Most __ is dictated by membrane potential
pmf
136
Valinomycin can move ___ but not ___
Charges
| Protons
137
How does valinomycin reduce membrane potential
By making K+ permeable across the inner membrane
138
After adding valinomycin, there is a net increase in ___ to compensate for the movement of K+ across the matrix
Movement of H+ protons
139
After adding valinomycin, there is a ___ in proton conductance across the membrane to sustain the same pmf
Increase
140
Proton current and respiratory rate are ___
Parallel
141
___ and ___ are stoichiometrly linked
Electron flow and proton pumping
142
Things that can influence pmf
Concentration of cations, weak acids, or anions
143
What does it mean that electron flow and proton pumping are stoichiometrically linked
There is a net movement of protons across the membrane per number of electrons flowing
144
There is a linkage between electron flow and ___
Oxygen consumption
145
Cytochrome C oxidase uses oxygen as a _____
Electron acceptor
146
Cytochrome C oxidase binds hydrogen protons to oxygen to form ___
Water
147
Mitochondria consume ___ present in the medium
Oxygen
148
Respiration is measured with __
Clark-type polarographic electrode
149
Clark-type polarographic electrode
Two pieces of metal (silver and platinum) separated physically in a salt solution (electrolyte)
150
Increased oxygen in the sample = __ oxygen flow = __ recording
Increased
| Increased
151
Decreased oxygen in the sample = ___ recording
Decreased
152
Another name for respiration
Oxygen consumption
153
Oxygen consumption under various states yield useful information regarding
pmf-generated and pmf-dissipating forces
154
Things that can be injected to measure respiratory states
Mitochondria, substrates (reducing agents), limited compounds (ADP), other inhibitors (to inhibit ATPase)
155
With additions, you will observe changes in the rate of ___ in the sample
Oxygen consumption
156
First respiratory state
Oxygen consumption associated with the addition of mitochondria
157
How are mitochondria generating membrane potential in the first respiratory state
Mitochondria is burning endogenous substrates
158
Oxygen in the chamber in the first respiratory state
Decreased
159
Second respiratory state
Substrates are added
160
What type of circuit is the second respiratory state like
Open
161
What is generated during the second respiratory state
Membrane potential (increased pmf)
162
Third respiratory state
ADP added
163
What type of circuit is the third respiratory state like
Closed
164
Why is the third respiratory state considered closed
ATPase has everything it needs to produce ATP
165
What happens to the membrane potential as protons are flowing back into the matrix in the third respiratory state
Slight dip
166
Membrane potential increases after the slight dip and continues to raise until ___
ADP is exhausted
167
What stage has the highest oxygen consumption rate
Third respiratory state
168
Fourth respiratory state
ADP exhaustion
169
What type of circuit is the fourth respiratory state like
Open
170
Respiratory rate when ADP is exhausted in state 4
Low
171
Fifth respiratory state
Runs out of oxygen
172
BAT impact on proton circuitry
Can short the circuit
173
What types of animals have BAT
Endotherms
174
Types of adipocytes
1. White
2. Beige
3. Brown
175
___ present in the inner membrane can short the circuit
Uncoupling proteins
176
How do uncoupling proteins short the circuit
Allow passage of protons across the membrane and dissipation of pmf
177
How does uncoupling affect electron transport system
High activity of electron transport system
178
How does uncoupling affect oxygen consumption
High oxygen consumption
179
How does uncoupling affect heat generation
High generation of heat
180
BAT is packed with mitochondria that have high expression of ___
Uncoupling protein 1
181
How many uncoupling proteins are there
3 types
182
All 3 types of adipocytes are under ___ control
Endocrine control
183
There is endocrine control of the production of ___
Free fatty acids
184
What do free fatty acids activate
Uncoupling proteins
185
pmf can be partitioned into forces that ___ and ___
Dissipate and generate
186
Generating forces example
Dehydrogenases responsible for producing reducing agents
187
Dissipating forces examples
- Dissipating membrane in an organized way and generating ATP in the process. ATP is translocated by adenosine nucleotide translocator
- Leak across the membrane (intrinsic or via uncoupling protein)
188
Dissipating forces can be ___ or ___ from ATP production
Coupled or uncoupled
