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Mitochondrial > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

pH

A

Concentration of protons in a particular medium

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2
Q

Primary role of adipose tissue in short circuiting the chemiosmotic proton circuit

A

Thermogenesis (production of heat)

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3
Q

Another name for potential difference

A

Protonmotive force

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4
Q

___ resembles a proton circuit

A

Electrical circuit

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5
Q

Electrical and proton circuits have a power source capable of moving electrons from __ to __

A

Cathode to anode (+ to -)

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6
Q

How are electrical and proton circuits ruled by the same forces

A

There is a potential gradient that could be generated

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7
Q

What is the potential gradient measured as in the mitochondria

A

Membrane potential

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8
Q

Membrane potential

A

Potential of the membrane to do work

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9
Q

Unit of potential difference

A

Volts/milivolts

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10
Q

Unit of current

A

Amps

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11
Q

Factors derived from potential difference and current

A

Energy transmission and resistance to components in a circuit

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12
Q

Unit of energy transmission

A

Watts

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13
Q

Unit of resistance of components in the circuit

A

Ohms

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14
Q

Which circuit is more complex: proton or electrical

A

Proton

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15
Q

Proton circuit resembles an electrical circuit with multiple ___

A

Batteries

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16
Q

Open circuit example

A

Battery is not connected to the appliance

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17
Q

What type of circuit is needed to perform useful work

A

Closed

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18
Q

Why is a closed circuit needed to perform useful work

A

Protons need to be channeled back

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19
Q

Factors that make the mitochondrial circuit complex

A

Multiple enzymes capable of pumping protons across the membrane, multiple batteries

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20
Q

Mitochondrial circuit battery layout

A

Parallel

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21
Q

Why do mitochondrial circuits have batteries arranged in parallel

A

Amplifies the ability of the battery top operate at a higher current

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22
Q

Voltage with batteries in parallel

A

Same voltage

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23
Q

Moving ___ of __ is all you need to generate pmf

A

1 nano mole of H+

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24
Q

___ is not directly capable of performing useful work

A

Open circuit

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25
Q

Does an open circuit have an electrical potential

A

Yes

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26
Q

Is there proton flow across the inner membrane back to the matrix in open circuit

A

No

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27
Q

What happens because there is no proton flow across the inner membrane in an open circuit

A

Protons will accumulate in the intermembrane space

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28
Q

Affect on pH when protons accumulate

A

pH can drop by 0.5

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29
Q

Redox potential

A

Potential of reduction and oxidation reactions occurring across the TCA cycle

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30
Q

__ are capable of being oxidized by proton pumps

A

Reducing agents

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31
Q

Potential of redox reactions will equal the ___

A

Electrical potential across the membrane

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32
Q

Redox potential balances ___

A

The electrical potential

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33
Q

Which circuit has the highest pmf

A

Open circuit

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34
Q

Why is the potential the highest in open circuit

A

The gradient is large

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35
Q

In which circuit is ATPase activated

A

Closed circuit

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36
Q

What does activation of ATPase lead to

A

Protons flow back into the matrix

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37
Q

In the closed circuit, pmf is slightly ___ than in open circuit

A

Lower

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38
Q

Can the closed circuit perform useful work with a lower pmf

A

Yes

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39
Q

Closed circuit is the equivalent of an electrical circuit being switched on/off

A

On

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40
Q

Which circuit describes the thermogenic function of BAT

A

Closed but shorted circuit

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41
Q

How does BAT short the circuit

A

Enzyme mediated (NOT with protonophores)

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42
Q

A closed but shorted circuit affects the amount of ___ and __ utilized

A

Reducing agents and O2

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43
Q

___ induce movement of protons across the membrane uncoupled from ATP production

A

Protonophores

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44
Q

How do protonophores induce movement of protons across the membrane uncoupled from ATP production

A

Poke holes in the inner membrane so H+ protons can flow

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45
Q

Pmf in the closed but shorted circuit

A

Slightly lower

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46
Q

Why is the pmf slightly lower in the closed but shorted circuit

A

Because protonophore tries to dissipate the gradient

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47
Q

Which circuit has the maximal electron flow

A

Closed but shorted circuit

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48
Q

Effect of fast electron flow in the closed but shorted circuit

A

Electron acceptor (oxygen) is used at a faster rate

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49
Q

Respiration of mitochondria in closed but shorted circuit

A

Maximal capacity

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50
Q

The electron transport system is strictly dependent on ___ derived from the ___

A

Substrates derived from the TCA

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51
Q

Another name for the TCA

A

Citric acid/krebs cycle

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52
Q

Substrates from the TCA cycle that fuel the pumping of protons across the inner membrane

A

Reducing agents

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53
Q

Redox potential is high when ___

A

Substrates are available

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54
Q

How can pmf be dissipated

A

Coupled or uncoupled to ATP synthesis

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55
Q

___ play an important role in redox reactions

A

Reducing agents

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56
Q

NADH donates electrons into ___

A

Complex I

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57
Q

Complex II

A

Succinate dehydrogenase

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58
Q

What does succinate produce

A

FADH2

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59
Q

FADH2 donates electrons into

A

Succinate dehydrogenase

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60
Q

Succinate dehydrogenase translocates electrons to____

A

Ubiquital Q pool

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61
Q

Mitochondrial dysfunction and associated diseases are usually tied to ___

A

Enzyme complexes and their functioning

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62
Q

Why is pmf measured

A

To assess metabolic function

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63
Q

Parameters that need to be evaluated to measure pmf

A
  • Electrical potential across a membrane

- Proton gradient across a membrane

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64
Q

Symbol for electrical potential across a membrane

A

delta ceptar

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65
Q

Symbol for proton gradient across a membrane

A

delta pH

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66
Q

What part is usually negative

A

Matrix

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67
Q

What part is usually positive

A

Intermembrane

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68
Q

Ion that contributes to overall positive charge in the intermembrane space besides H+

A

K+

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69
Q

Per every 1 nanomole moved across the membrane, monovalent ions increase ___ fold every __ mV

A

10-fold every 60mV

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70
Q

Electrical potential of a membrane

A

60 mV

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71
Q

Measure of membrane potential is based on the charge inside/outside of the membrane

A

Inside

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72
Q

Many techniques of measuring pmf have been developed since ___

A

1969

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73
Q

Methods of measuring pmf

A
  • Ion specific electrodes to measure delta ceptar (electrical potential)
  • Radioisotope technique
  • Optical indicators of delta ceptar (electrical potential)
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74
Q

Ion specific electrode method dates back to ___

A

1969

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75
Q

Why is ion selection crucial in ion specific electrode method

A
  • Must have the right charge
  • Must achieve electrochemical equilibrium rapidly
  • Needs to move across membrane by a single mechanism
  • Cannot be metabolized
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76
Q

What charge must ions have in the ion specific electrode method

A

Cation (positive)

77
Q

To move across the membrane rapidly, the selected ion must be __ in nature

A

Hydrophobic

78
Q

Mechanisms of moving ions across the membrane

A

Protein-mediated and bilayer-mediated

79
Q

Why cant the selected ion be metabolized

A

You do not want the indicator to be used up

80
Q

Most commonly used ions in the ion specific electrode method

A

TPP+ and TPMP+

81
Q

Group that both TPP+ and TPMP+ have

A

Phosphonium group

82
Q

Phosphonium is hidden by ____

A

Hydrophobic groups

83
Q

In the ion specific electrode method, ions are coupled to

A

Electrodes

84
Q

In electrodes, anoids and cathoids are separated by ___

A

Salt solution

85
Q

TPP+ and TPMP+ are accumulated and quantified in ___

A

Intermembrane space

86
Q

TPP+ and TPMP+ ___ over time

A

Decrease

87
Q

TPP+ and TPMP+ move across the membrane into the ___

A

Matrix

88
Q

Changes in the concentrations of ___ can be used to calculate pmf

A

Cations

89
Q

In order to calculate the pmf, there has to be a way to calculate the __ of the matrix

A

Volume

90
Q

Radioisotope technique is modified from ___

A

Ion-selective assay

91
Q

Radioisotopes used in radioisotope technique

A

Rubidium and 3H

92
Q

What is 3H

A

Hydrogen with 3 protons

93
Q

3H is used in the formation of ___ in the electron transport system

A

Water

94
Q

___ is used as a control in the radioisotope technique

A

14C sucrose in pellet (sucrose labeled with C14)

95
Q

Sucrose is a ___

A

Carbohydrate

96
Q

Is sucrose permeable to the phospholipid bilayer

A

No

97
Q

How can you get a sucrose pellet

A

After centrifugation of cells with mitochondria in incubation medium and silicone oil

98
Q

Mitochondria are incubated with ___

A

Radioisotopic compounds

99
Q

What equation is used in the radioisotope technique

A

Nernst equation

100
Q

Nernst equation

A

Equilibrium equation

101
Q

What is used in the radioisotope technique

A

Nernst equation and space used by the radio-labeled sucrose, TPP+, and H+ in the pellet

102
Q

Radiolabeled water in the Nernst equation

A

Vh

103
Q

What is the Nernst equation used to estimate

A

The overall volume of the matrix and membrane potential

104
Q

How are optical indicators of delta ceptar used

A

To evaluate changes in the membrane potential associated with pmf

105
Q

Mitchell estimated membrane potentials of about ___ in an open circuit

A

200 mV

106
Q

A membrane potential of 200 mV results in an electrical potential of _____

A

300,000 volts per cm

107
Q

___ can alter the orientation/shape of specialized components within the membrane

A

Strong electrical fields

108
Q

What is the result of altered orientation/shape of specialized components within the membrane

A

Change of spectral properties

109
Q

Membrane bound components that can change with strong electrical fields

A

Carotenoids in chloroplasts and lipophilic ions on mitochondria

110
Q

Example of lipophilic ion

A

TMRM+

111
Q

How to observe spectral properties

A

Apply dual wavelength spectrophotometers

112
Q

Dual wavelengths for lipophilic ions

A

Lambda 1 and 2

113
Q

Different wavelengths are observed in different ___

A

Respiratory states

114
Q

More mitochondria = ___ flourescence ratio

A

Higher

115
Q

More ADP = ___ membrane potential

A

Decreased

116
Q

Addition of FCCP = ___ membrane potential

A

Decreased

117
Q

Why is there decreased membrane potential with the addition of FCCP

A

pmf is low because it cannot retain protons on one side of the membrane

118
Q

Every time there is a change in the membrane potential, there is a change in the ___ between the two wavelengths

A

Flourescence ratio

119
Q

___ can be used as an indicator of membrane potential

A

Flourescense ratio

120
Q

Respiratory state

A

Refers to oxygen consumption in a specific scenario

121
Q

Other ___ can move across the inner membrane and affect the controllers of pmf

A

Charged particles

122
Q

Forces can either ___ or ___ pmf

A

Dissipate or generate

123
Q

___ and ___ can be used to calculate pmf

A

delta pH and membrane potential

124
Q

Deenergized mitochondria

A

Pumps not fueled by substrates

125
Q

pmf in deenergized mitochondria

A

0

126
Q

Membrane potential in deenergized mitochondria

A

0 (no electrical potential)

127
Q

Delta pH in deenergized mitochondria

A

0 (the pH is not 0, but the change in pH is > no net pumping of protons to alter pH)

128
Q

What ions balance charges

A

Other cations (mostly K+)

129
Q

1 nanomole of H+ pumped results in a delta ceptar of

A

200 mV

130
Q

Ion permeant reduces __ and __, which is compensated by increased ___

A

delta ceptar
pmf
delta pH

131
Q

Uptake of ___ in response to high pH dissapates the pH gradient, restoring ___ but inducing mitochondrial swelling

A

Weak acids

delta ceptar

132
Q

Reducing agents generate a ___

A

Gradient

133
Q

___ change in pH when reducing agents are added

A

Very low

134
Q

Matrix is made more ___ when reducing agents are added

A

Negative

135
Q

Most __ is dictated by membrane potential

A

pmf

136
Q

Valinomycin can move ___ but not ___

A

Charges

Protons

137
Q

How does valinomycin reduce membrane potential

A

By making K+ permeable across the inner membrane

138
Q

After adding valinomycin, there is a net increase in ___ to compensate for the movement of K+ across the matrix

A

Movement of H+ protons

139
Q

After adding valinomycin, there is a ___ in proton conductance across the membrane to sustain the same pmf

A

Increase

140
Q

Proton current and respiratory rate are ___

A

Parallel

141
Q

___ and ___ are stoichiometrly linked

A

Electron flow and proton pumping

142
Q

Things that can influence pmf

A

Concentration of cations, weak acids, or anions

143
Q

What does it mean that electron flow and proton pumping are stoichiometrically linked

A

There is a net movement of protons across the membrane per number of electrons flowing

144
Q

There is a linkage between electron flow and ___

A

Oxygen consumption

145
Q

Cytochrome C oxidase uses oxygen as a _____

A

Electron acceptor

146
Q

Cytochrome C oxidase binds hydrogen protons to oxygen to form ___

A

Water

147
Q

Mitochondria consume ___ present in the medium

A

Oxygen

148
Q

Respiration is measured with __

A

Clark-type polarographic electrode

149
Q

Clark-type polarographic electrode

A

Two pieces of metal (silver and platinum) separated physically in a salt solution (electrolyte)

150
Q

Increased oxygen in the sample = __ oxygen flow = __ recording

A

Increased

Increased

151
Q

Decreased oxygen in the sample = ___ recording

A

Decreased

152
Q

Another name for respiration

A

Oxygen consumption

153
Q

Oxygen consumption under various states yield useful information regarding

A

pmf-generated and pmf-dissipating forces

154
Q

Things that can be injected to measure respiratory states

A

Mitochondria, substrates (reducing agents), limited compounds (ADP), other inhibitors (to inhibit ATPase)

155
Q

With additions, you will observe changes in the rate of ___ in the sample

A

Oxygen consumption

156
Q

First respiratory state

A

Oxygen consumption associated with the addition of mitochondria

157
Q

How are mitochondria generating membrane potential in the first respiratory state

A

Mitochondria is burning endogenous substrates

158
Q

Oxygen in the chamber in the first respiratory state

A

Decreased

159
Q

Second respiratory state

A

Substrates are added

160
Q

What type of circuit is the second respiratory state like

A

Open

161
Q

What is generated during the second respiratory state

A

Membrane potential (increased pmf)

162
Q

Third respiratory state

A

ADP added

163
Q

What type of circuit is the third respiratory state like

A

Closed

164
Q

Why is the third respiratory state considered closed

A

ATPase has everything it needs to produce ATP

165
Q

What happens to the membrane potential as protons are flowing back into the matrix in the third respiratory state

A

Slight dip

166
Q

Membrane potential increases after the slight dip and continues to raise until ___

A

ADP is exhausted

167
Q

What stage has the highest oxygen consumption rate

A

Third respiratory state

168
Q

Fourth respiratory state

A

ADP exhaustion

169
Q

What type of circuit is the fourth respiratory state like

A

Open

170
Q

Respiratory rate when ADP is exhausted in state 4

A

Low

171
Q

Fifth respiratory state

A

Runs out of oxygen

172
Q

BAT impact on proton circuitry

A

Can short the circuit

173
Q

What types of animals have BAT

A

Endotherms

174
Q

Types of adipocytes

A
  1. White
  2. Beige
  3. Brown
175
Q

___ present in the inner membrane can short the circuit

A

Uncoupling proteins

176
Q

How do uncoupling proteins short the circuit

A

Allow passage of protons across the membrane and dissipation of pmf

177
Q

How does uncoupling affect electron transport system

A

High activity of electron transport system

178
Q

How does uncoupling affect oxygen consumption

A

High oxygen consumption

179
Q

How does uncoupling affect heat generation

A

High generation of heat

180
Q

BAT is packed with mitochondria that have high expression of ___

A

Uncoupling protein 1

181
Q

How many uncoupling proteins are there

A

3 types

182
Q

All 3 types of adipocytes are under ___ control

A

Endocrine control

183
Q

There is endocrine control of the production of ___

A

Free fatty acids

184
Q

What do free fatty acids activate

A

Uncoupling proteins

185
Q

pmf can be partitioned into forces that ___ and ___

A

Dissipate and generate

186
Q

Generating forces example

A

Dehydrogenases responsible for producing reducing agents

187
Q

Dissipating forces examples

A
  • 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
Q

Dissipating forces can be ___ or ___ from ATP production

A

Coupled or uncoupled

Mitochondrial (5 decks)

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