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BICH 411 > EXAM 2 > Flashcards

EXAM 2 Flashcards

1
Q

what are different ways we can generate acetyl CoA

A

Carbohydrates
Fatty Acids
Amino Acids

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2
Q

Acetyl CoA ____ in the TCA cycle, where intermediates are utilized in a _________ _________

A

oxidized, circular pathway

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3
Q

what is the primary determinant in fate of pyruvate in humans?

A

O2 levels

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4
Q

what is the most important molecule that fuels the TCA cycle

A

acetyl CoA

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5
Q

Draw Acetyl CoA

A

slide 3 on PDHC

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6
Q

Glycolysis occurs in ______ and does not require ______

A

cytoplasm, oxygen

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7
Q

Glycolysis generates a net of how many ATP and how many pyruvates?

A

2 ATP , 2 Pyruvate

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8
Q

TCA cycle allows for _______ of _______ to _____ under _____ conditions

A

oxidation, pyruvate, CO2, aerobic

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9
Q

where does the TCA cycle occur

A

mitochondrial matrix

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10
Q

electron movement of the ETC is couple with

A

the pumping of H+ aka PMF creating a large H+ gradient

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11
Q

what needs to occur before fueling TCA

A

pyruvate is converted to acetyl-CoA

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12
Q

What is occuring in the TCA (general)

A

acetyl-coA oxidized to CO2 and electrons are stored as NADH and FADH2

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13
Q

Since electrons are stored as NADH and FADH2 where do they go ?

A

ETC

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14
Q

What is the final electron acceptor of ETC

A

Oxygen

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15
Q

what drives synthesis of ATP of TCA and what is this process known as

A

coupling of proton gradient across the membrane with electrons , known as oxidative phosphorylation

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16
Q

Characteristics of Inner mitochondrial membrane

A

impermeable to almost everything

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17
Q

why is it important for the IMM to be impermeable to almost everything

A

it allows for moving of e- in a spont. direction to utilize the energy to force the pumping of e- against [ ] gradient creating an increase of proton gradient b/w IMM and matrix

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18
Q

what is the ultimate fate of the carbons from the glucose that fuels glycolysis

A

CO2 as a waste product

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19
Q

complete oxidation of glucose to CO2 involves removal of how many electrons? what does this mean?

A

24 e-, means that process is a 24 e- rich oxidation

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20
Q

how many total electrons are produced in glycolysis

A

4

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21
Q

how many total electrons are produced by PDHC

A

4

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22
Q

How many electrons are produced for each acetyl CoA in TCA

A

8

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23
Q

what molecules are used to fuel oxidative phosphorylation

A

NADH and FADH2

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24
Q

How many electrons does NADH always transfer at a time

A

2 e-

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25
Q

Draw the mechanism for the oxidation of NADH

A

slide 10 on PDHC

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25
Q

draw the mechanism for the reduction of NAD+

A

slide 10 on PDHC

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26
Q

Draw FAD

A

SLIDE 20 on PDHC

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27
Q

why can flavin coenzymes participate in SET or 2 e- transfer rxns

A

it can exist in three oxidation states

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28
Q

why do we prefer 2 e- transfer rxns over SET in flavin coenzymes

A

because SET form radicals which are highly reactive and can react with anything they touch

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29
Q

from what vitamin do we get FADH2

A

riboflavin

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30
Q

what is the source of acetyl CoA

A

pyruvate

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31
Q

what enzyme is able to covert pyruvate to acetyl-CoA

A

Pyruvate Dehydrogenase Complex

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32
Q

outer mitochondrial membrane is permeable to

A

anything smaller than 5 kD

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33
Q

since the IMM is highly impermeable what are the only molecules it permeable to

A

O2, H2O, CO2

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34
Q

In order for pyruvate to come into the matrix what must it use

A

transport protein known as pyruvate/H+ symporter

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35
Q

define Pyruvate/H+ symporter

A

movement of H+ and Pyruvate in the same direction into the matrix

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36
Q

what are the three enzymes that make up the PDHC

A

Pyruvate DH (E1)
Dihydrolipoyl transacetylase (E2)
dihydrolipoyl DH (E3)

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37
Q

Draw TPP

A

slide 20 on PDHC

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38
Q

Draw CoA

A

slide 20 on PDHC

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39
Q

Draw Lipoic Acid

A

slide 20 on PDHC

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40
Q

function of CoA

A

carrier of acetyl and other acyl groups
accepts acetyl group from Lipoamide

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41
Q

T/F PDHC is irreversible and therefore regulated

A

T

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42
Q

draw out the diagram that summarizes the PDHC reactions

A

slide 21 on PDHC

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43
Q

function and location of TPP

A

E1, Decarboxylates pyruvate yielding a hydroxyethyl TPP carbanion

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44
Q

function of lipoamide

A

swinging arm to facilitate redox chemistry

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45
Q

function of NAD+ in PDHC

A

mobile e- carrier

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46
Q

T/F CoA serves to generate a thioester bond with energy roughly = to ATP

A

T

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47
Q

Beriberi is caused by

A

TPP/Vitamin B1(Thiamine) deficiency

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48
Q

symptoms of beriberi

A

pain
paralysis
wasting
heart failure

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49
Q

who are susceptible to beriberi

A

ppl who eat only white rice
alcoholics

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50
Q

what does the energy of thioester of CoA roughly equivalent to in energy terms

A

ATP

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51
Q

why would alcoholics be deficient in TPP

A

absorption
storage
metabolism
activation of many vitamins

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52
Q

location and function of lipoic acid

A

covalently linked to a Lys residue on E2, accepts the hydroxyethyl carbanion from TPP as an acetyl group

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53
Q

FAD location and function in PDHC

A

E3, reduced by lipoamide

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54
Q

disadvantages of FADH2

A

not a mobile e- carrier it is associated with an enzyme

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55
Q

function of FADH2 in PDHC

A

transfers e- to NAD+ forming NADH

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56
Q

Propose a mechanism for dihydrolipoyl DH ( Draw FADH2 and NAD+)

A

look at journal

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57
Q

Equation for electrochemical potential, identify which is the chemical and which is the electrical potential

A

∆G’ = RTln ([A destination]/[A source]) + (ZF(Membranepotential))

first half is chemical
second half is electrical

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58
Q

what is the importance of pyruvate/H+ symporter

A

ATP synthesis
Retrograde signalin
Quality Control System
Anion outward transport and Cation inward transport

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59
Q

Why so we care about membrane potential

A

long lasting drop or rise of normal levels may induce unwanted loss of cell viability and cause pathologies

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60
Q

role of mitochondrial membrane potential

A
  1. factor in selection of nonfunctional mitochondria
  2. drives inward transport of cations and outward transport of anions
  3. reestablishing of membrane potential
  4. want to trigger apoptosis in case of heterogeneity of membrane potential that may be a sign of pathology
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61
Q

entry of new carbon units into the TCA cycle is from ?

A

pyruvate or oxidation of FAs

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62
Q

Transfer of the 2-C acetyl-CoA to 4-C OAA yields

A

citrate

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63
Q

what kind of rearrangement yields isocitrate

A

the movement of 1 -OH group down on carbon

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64
Q

two successive decarboxylation of TCA produce

A

a-KG and then succinyl-CoA

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65
Q

T/F multiple rearrangements need to take place in TCA in order for regeneration of OAA

A

T

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66
Q

What is the first metabolite produced in TCA

A

Citrate

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67
Q

What is the last intermediate produced in TCA

A

Oxaloacetate

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68
Q

what is the enzyme that is considered the first reaction wher 2-C units of acetyl CoA are introduced to TCA by addition of 4C unit OAA to form citrate

A

citrate synthase

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69
Q

citrate synthase is classic chemistry of what molecule

A

CoA

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70
Q

Describe the citrate Synthase mechansim

A
  1. Ca of acetyl group in acetyl CoA is acidic and can be deprotonated to form carbanion
  2. then carbanion does nucleophilic attact on a-carbonyl of OAA
  3. Intermediate citryl-CoA is produced
  4. Thioester hydrolysis produce citrate
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71
Q

what enzyme of TCA undergoes a thioester hydrolysis

A

Citrate synthase

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72
Q

Function of citrate synthase

A

reaction that initiates TCA and produces citrate from OAA and acetyl-CoA

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73
Q

what enzyme mechanism of TCA cycle can be best described by an isomerization reaction that utilizes water for net conversion of tertiary alcohol to secondary alcohol

A

Aconitase

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74
Q

aconitase function

A

isomerizes citrate to yield isocitrate which can be oxidized

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75
Q

what enzymes use an iron sulfur cluster to dictate stereospecificity

A

aconitase
succinate DH

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76
Q

function of iron-sulfer cluster

A

aids in stereochemistry specificity of enzymatic reactions
facilitates redox rxn and transfer of e-
serve as e- carriers of complexes in ETC

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77
Q

what enzyme contains cis-aconitate intermediate in their mechanism

A

Aconitase

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78
Q

why is it important for citrate to undergo a change in stereochemistry

A

need for a-KGDH rxn to occur

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79
Q

function of isocitrate DH

A

first link to the ETC because it is where first NADH is produce

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80
Q

which enzyme mechanism contains oxalosuccinate as an intermediate

A

Isocitrate DH

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81
Q

Describe the mechanism of Isocitrate DH

A
  1. first their is oxidation of C2 OH of isocitrate to form oxalosuccinate
  2. then a b-decarboxylation rxn to expel the CO2 group
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82
Q

what enzyme mechanism is a classic NAD+ chemistry that involves hydride removal followed by decarboxylation

A

Isocitrate DH

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83
Q

Where does the CO2 release com form the enzyme mechanism of Isocitrate DH

A

OXAL

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84
Q

what enzyme catalyzes the second oxidative decarboxylation of TCA

A

a-ketoglutarate DH complex

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85
Q

what enzyme does a-ketogluterate DH Complex most resemble

A

PDHC

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86
Q

What are the 5 coenzymes/cofactors used in aKDHC

A

TPP
CoASH
Lipoic acid
NAD+
FAD

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87
Q

What are the enzymes that make up the aKDHC

A

a-ketoglutarate DH
dihydrolipoyl transsuccinylase
dihydrolipoyl DH

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88
Q

where is the second NADH produced

A

a-KDHC

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89
Q

if you replace the top two carbons of aKetoglutarate wht will happen

A

it will form pyruvate

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90
Q

function of aKDH and location

A

oxidative decarboxylation , E1

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91
Q

Function of dihydrolipoyl transuccinlyase and location

A

transfer of succinyl group, E2

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92
Q

Function of dihydrolipoyl DH in aKDHC and location

A

regenerate lipoamide , E3

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93
Q

what enzyme harvest high energy thioester bond to make GTP which later makes ATP

A

Succinyl-CoA synthetase

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94
Q

T/F succinyl-CoA is symmetric and therefor we can no longer distinguish which carbons came from acetyl-CoA

A

F, it is succinate

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95
Q

how would you categorize the reaction/mechanism of succinyl-CoA synthetase

A

substrate level phosphorylation

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96
Q

what enzyme mechanism is driven by hydrolysis of CoA ester

A

Succinyl-CoA synthetase

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97
Q

T/F Citrate is a great substrate for oxidation

A

F, it is a poor substrate

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98
Q

what enzyme produces the first NADH of the TCA

A

Isocitrate DH

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99
Q

where is the second NADH produces in the TCA

A

aKGDHC

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100
Q

why can we no longer distinguish which carbons came from acetyl-CoA in succinate

A

it is a symmetric molecule

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101
Q

what enzyme mechanism involves the formation of a phosphohistidine to produce succinate

A

Succinyl-CoA synthetase

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102
Q

what enzyme produces a nucleotide triphosphate in TCA

A

Succinyl-CoA Synthetase

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103
Q

what are disadvantages of FADH2

A

not mobile e- carrier
produces less ATP than NADH

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104
Q

what enzyme produces an FADH2

A

Succinate Dehydrogenase

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105
Q

how do you calculate standard free energy given reduction potentials

A

∆G’ = -nF(∆E’)

where n represents number of e- transferred

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106
Q

How do you calculate ∆E’

A

E’(acceptor) - E’ (donor)

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107
Q

name the enzyme in which the mechanism involves a hydride removal by FAD

A

Succinate DH

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108
Q

What enzyme of TCA is also part of the ETC , specifically Complex II, found in the IMM

A

Succinate DH

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109
Q

the e- transferred from succinate to FAD ( to form FADH2) are passed directly to …… ? in order to get to the ETC

A

Ubiquinone

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110
Q

List the enzymes that are fully reversible in TCA cycle and are utilized for the rearrangement of carbon skeletons

A

Fumarase
Malate DH

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111
Q

What enzyme mechanism uses water to rearrange its carbon skeletons and form malate

A

Fumarase

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112
Q

T/F the actual mechanism for fumarase is known

A

F, it is not known for certain

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113
Q

In a proposed enzyme mechanism of Fumarase what is the intermediate formed before it becomes malate

A

carbanion

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114
Q

malate gets oxidized or reduces to form Oxaloacetate?

A

Oxidized

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115
Q

what enzyme mechanism is classified as an NAD+- dependent oxidation reaction

A

Malate DH

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116
Q

In the Malate DH reaction, what carbond gets oxidized

A

the one that received an OH group from the previous reaction done by Fumarase

117
Q

describe the mechanism for malate DH

A

H of OH group on malate attacks NAD+ and O group forms double bond letting the another H leave forming OAA and NADH

118
Q

what are the substrates for citrate synthase

A

oxaloacetate and acetyl coA

119
Q

Name the two allosteric regulators of Pyruvate DH ( not talking about covalen modification)

A

NADH and Acetyl CoA

120
Q

if both NADH and Acetyl CoA levels are low how does this affect PDH?

A

It will be active

121
Q

draw a simple diagram of how PDHC is covalenty modified

A

slide 9 on Regulation

122
Q

what are the two ways we can covalently modify PDHC

A

Pyruvate DH kinase
Pyruvate DH phoshpatase

123
Q

what activates Pyruvate DH kinase and how does this affect PDHC

A

high levels of NADH, Acetyl CoA, and ATP

PDHC will be inactivated

124
Q

what is the mode of action that Pyruvate DH kinase is being regulated

A

Serine Residue of E1-PDH Phosphorylate, bound to complex

125
Q

what inhibits Pyruvate DH kinase and how does this affect PDHC

A

high levels of pyruvate , NAD+, Ca2+, and ADP

PDHC complex on

125
Q

What activates pyruvate dehydrogenase phosphatase and how does this affect the PDHC

A

high levels of Ca2+, pyruvate, NAD+, ADP, and insulin

PDHC is on

126
Q

What inhibits pyruvate dehydrogenase phosphatase and how does this affect the PDHC

A

high levels of ATP, NADH, and acetyl-CoA

PDHC is off

127
Q

what covalent modification enzyme blocks the decarboxylation of pyruvate and halts the formation of acetyl-CoA

A

Pyruvate DH Kinase

128
Q

How does the pyruvate DH phosphatase activate PDHC

A

hydrolyzes the phosphorylated serine of E1 by using calcium to bind to the complex ( without it , it won’t be able to associate with the complex)

129
Q

T/F PDHC is covalently regulated by allosterically controlled enzymes

A

T

130
Q

in terms of TCA enzymes, what is inhibited by high levels of NADH

A

PDHC, Citrate-Synthase, aKGDHC

131
Q

what complex is inhibited by high levels Acetyl-CoA

A

PDHC

132
Q

in terms of TCA enzymes, what is inhibited by high levels of citrate

A

citrate synthase

NOTE: also inhibits glycolytic enzyme PFK1

133
Q

in terms of TCA enzymes, what is inhibited by high levels of high levels of Succinyl CoA

A

Citrate synthase and aKGDHC

134
Q

in terms of TCA enzymes, what is inhibited by high levels of ATP

A

Isocitrate DH

135
Q

in terms of TCA enzymes, what is activated by high levels of calcium

A

Isocitrate DH and aKGDH

136
Q

Why is Ca++ important

A

signals muscle contraction and allows for production of ATP for fuel

137
Q

what inhibits citrate synthase

A

high levels of ATP, NADH, and Succinyl-CoA

138
Q

what inhibits isocitrate dehydrogenase

A

high level of ATP

139
Q

what activates isocitrate DH

A

high levels of ADP, Ca++, and NAD+

140
Q

what inhibits aKGDH

A

high levels of NADH and Succinyl-CoA

141
Q

what activates aKGDH

A

High levels of AMP and Calcium

142
Q

what activates citrate synthase

A

high levels of ADP

143
Q

T/F another function of TCA cycle is to provide intermediates to fuel catabolic pathways

A

F, it is biosynthetic pathways (anabolism)

144
Q

what other pathways can citrate feed off to?

A

Fatty Acids (B-oxidation)
Cholesterol

145
Q

what pathway can a-ketoglutorate feed of to and what pathway can feed into it

A

Amino Acids
NT synthesis of Purines ( A and G )

146
Q

what pathway can succinyl-CoA feed off to

A

Porphyrins (O2 transport)

147
Q

what pathways feed into succinyl-CoA (Hint: list the specific Amino Acids)

A

Odd-chain FAs
Isoleucine , Methionine, and Valine

148
Q

what specific amino acids feed into fumarate

A

aspartate
tyrosine
phenylalanine

149
Q

what pathway can feed into Oxaloacetate

A

Amino Acid

150
Q

what pathway can oxaloacetate feed off too

A

Amino Acids
TO MALATE for Filling up RXn

151
Q

Malate can feed off to what pathway

A

Glucose

152
Q

Draw a simple diagram for the anaplerotic Reactions

A

slide 25 on Regulation

153
Q

what are the three enzymes that catalyze the anaplerotic reaction that replenish TCA cycle intermediates

A

PEP carboxylase
Pyruvate carboxylase
Malic Enzyme

154
Q

PEP carboxylase function in anaplerotic rxns

A

converts PEP to oxaloacetate

155
Q

Pyruvate carboxylase function in anaplerotic rxns

A

converts pyruvate to OAA

156
Q

Malic Enzyme function in anaplerotic rxns

A

converts pyruvate into malate

157
Q

What is the purpose of the anaplerotic reactions?

A

Replenish TCA cycle intermediates.

When we have high concentrations of pyruvate we want it to be converted to Acetyl-CoA so it can be consumed creating more e- carriers and allowing for energy to be synthesized!

158
Q

what are the two routes in the malate aspartate shuttle

A
  1. Aspartate aminotransferase
  2. Malate DH
159
Q

What does aspartate aminotransferase do in the matrix and in the cytosol?

A

converts OAA to aspartate in the matrix using an amino acid and releasing a-keto acid

in the cytosol aspartate is converted to OAA by a-keto acid reacting with aspartate releasing amino acid making OAA

160
Q

how is aspartate aminotransferase different from malate DH

A

Does not require NAD/NADH
deals with moving nitrogen

161
Q

how is malate DH different from aspartate aminotransferase

A

requires NAD/NADH
deals with moving e-

162
Q

draw simple diagram for malate-aspartate shuttle

A

slide 30 on Regulation slide

163
Q

draw simple diagram for glycerophosphate shuttle

A

slide 31 on regulation slides

164
Q

when will the glycerophosphate shuttle be active

A

active when we need to make ATP as fast as possible ( doing physical activity)

165
Q

what shuttle results in the loss of 1 ATP

A

Glycerophosphate

166
Q

when will the malate aspartate shuttle be active

A

in a relaxed state

167
Q

What are the three steps of Glycerophosphate shuttle

A
  1. ketones converted to alcohol
  2. OH converted back to ketone
  3. FADH2 trasports 2e- to ETC
168
Q

Function of 3-Phosphoglycerol DH

A

Oxidizes NADH while converting DHAP (ketone) to 3-Phosphoglycerol (alcohol)

169
Q

Function of flavoprotein DH ( has two functions)

A
  1. FAD reacts with 3PG , converting 3PG (alcohol) to DHAP (ketone), while being reduced FADH2
  2. Allows for FADH2 to do 2e- transfer to ETC
170
Q

T/F FADH2 is part of flavoprotein DH that transports 2e- to ETC

A

T

171
Q

Glyoxylate Cycle is done by ,

A

plants and some bacteria

172
Q

how is Glyoxylate cycle different from TCA

A

CO2 releasing steps are bypassed and an extra acetate is utilized

173
Q

what are the short-circuiting enzymes in the Glyoxylate cycle

A

Isocitrate lyase and malate synthase

174
Q

what enzymes do isocitrate lyase and malate synthase replace from TCA

A

Isocitrate DH and a-KGDHC

175
Q

what carbon source do plants rely the most on

A

acetate

176
Q

Draw all the intermediates of the TCA cycle

A

look at TCA powerpoint slides

177
Q

Draw ETC showing pumping of H+ , NADH, FADH2

A

look at ETC slides

178
Q

How many protons = 1 ATP

A

4 H+

179
Q

If 4H+ = 1 ATP, where do we get the 4 H+ from

A

1 H+ to transport ATP out
3 H+ from ATP synthesis via ATP synthase

180
Q

How do we get 2.5 ATP per 1 NADH ?

A

10 H+ ( from ETC) / ( 4 H+/1 ATP) = 2.5 ATP

181
Q

How do we get 1.5 ATP per 1 NADH?

A

6 H+ (from ETC) / ( 4 H+/1 ATP) = 1.5 ATP

182
Q

what transports ATP out of the matrix to the IMM space ?

A

a translocase

183
Q

why is the ATP movement favored out of the matrix

A

ATP movement is favorable out of the matrix because the IMM space is positively charged compared to the negatively charged matrix

184
Q

what amino acid is responsible for picking up H+ from the IMM Space in ATP Synthase (include the specific subunit)

A

Aspartate subunit C

185
Q

Describe how Aspartate is used in ATP synthase

A
  1. aspartate becomes protonated by picking up H+ ( becomes aspartic acid)
  2. causes a clockwise rotation
  3. As rotation continues it approaches subunit c where it can transfer a H+ to Ser
  4. H+ becomes released
186
Q

How many ATP are created by a 360° rotation of gamma subunit of ATP synthase?

A

3 ATP

187
Q

How many ATP are created by a 2 revolutions of gamma subunit of ATP synthase?

A

6 ATP

( 1 revolution = 3 120 ° rotations = 3 ATP , just multiply by 2)

188
Q

Characteristics of F0 in ATP synthase

A

membrane bound
allows for the favorable movement of H+ to induce conformational changes in F1

189
Q

Characteristics of F1

A

on the matrix side
3 aB active sites where ADP+P bind to create ATP

190
Q

describe the order of the binding sites in the aB subunits of ATP synthase

A

L –> T —> O

191
Q

L ( loose) binding site function

A

where ADP+ Pi bind

192
Q

T ( tight ) binding site function

A

where the chemistry happens forming ATP

193
Q

O ( nonbinding) site function

A

where ATP is release from going back to its original state

194
Q

function of y-subunit

A

rotates 120° degree for aB subunits to have 3 distinct conformations

195
Q

membrane potential equations in terms of protons

A

∆ G = RT∆PH + ZF(∆MP)

196
Q

how many protons are pumped out of the matrix per NADH?

A

10 H+

197
Q

how many protons are pumped out of the matrix per FADH2?

A

6 H+

198
Q

Define repirasomes

A

they are multimeric supercomplexes
that function in a state where two or more complexes are associated

199
Q

Why is it important for ETC to have supercomplexes like repirasomes

A
  1. greater efficiency for ATP production and respiration
  2. presence of certain complexes positively influence other complexes
200
Q

how many electrons are transferred in a complete Q-cycle

A

4 e- are transferred sequentially , S.E.T

201
Q

Why is it important for complex IV to transfer electrons in batches of 4

A

shields the rest of the cell from reactive intermediates

202
Q

O2- , H2O2, OH- + OH are all examples of

A

reactive oxygen species (ROS)

203
Q

which complex produces the least amount of ROS? How about the complex that produces the most?

A

Complex IV

Complex I

204
Q

cytochrome c reduces what complex?

A

complex IV

205
Q

what oxidizes complex IV

A

O2

206
Q

what are the e- carriers in complex IV

A

cytochromes
copper

207
Q

Function of complex IV

A

pumps 2 H+ across mitochondria inner membrane

208
Q

Cytochrome C oxidase is in what complex

A

Complex IV

209
Q

Cytochrome C characteristics

A

mobile e- carrier
water soluble

210
Q

where can cytochrome C be found

A

associated on the inner mitochondrial membrane space

211
Q

function of cytochrome c

A

shuttles electrons from complex III to complex IV

212
Q

draw the first half of the Q cycle

A

slide 26 ETC presentation

213
Q

draw the second half of the Q cycle

A

slide 27 ETC presentation

214
Q

UQH2 —> Rieske Fe-S —> Cyt c.

occurs where?

A

first half of the Q cycle

215
Q

what occurs in the first half of the Q cycle?

A
  1. QH2 travels across the inner mitochondrial membrane and donates 1 e- and 2 H+
  2. QH2 IS oxidized to Q●- and stays inside the membrane
  3. 1 e- then is transferred to bL heme –> bH heme
216
Q

what occurs in the second half of Q cycle

A
  1. 2nd QH2 travels across the inner mitochondrial membrane and donates 1 e- to bH and 2 H+ are released
  2. QH2 oxidized to Q●- and reacts with the first Q●- to produce QH2 and Q
217
Q

what are the different fates of QH2 and Q in the Q cycle?

A

Q will go back to Complex I or II to pick up e-

QH2 will travel across the inner mitochondrial membrane and start the cycle again

218
Q

function of complex III

A

mediates electron transport from Coenzyme Q to Cytochrome c

219
Q

Coenzyme Q - cytochrome c oxidoreductase is found in what complex

A

complex III

220
Q

What reduces and oxidizes complex III

A

QH2 reduces
Cytochrome C is oxidizes

221
Q

what are the e- carriers found in complex III

A

FeS
cytochromes

222
Q

what is the principal transmembrane protein in complex III

A

b cytochrome with hemes bL and bH

223
Q

CoQ passes electrons to ____ in a unique redox cycle known as the ____ ______

A

Cytochrome C
Q cycle

224
Q

How many protons are pumped from Complex III

A

4 H+

225
Q

Succinate-coenzyme Q oxidoreductase is found in

A

Complex II

226
Q

T/F complex II utilizes Fe-S clusters and hemes to move e-s

A

T

227
Q

How is Complex II different from the other three complexes

A

it does not pump protons across to the IMM space

228
Q

what complex reduces FADH2 to Q forming QH2

A

Complex II

229
Q

why does complex II take its e-s from FADH2 and not NADH

A

it takes less energy to reduce FADH2 than NADH

230
Q

How many protons are released from complex I

A

4 H+

231
Q

in what complex does this occur

NADH —> Complex I —-> QH2

A

Complex I

232
Q

What complexes strips off e-s from NADH ?

A

Complex I

233
Q

what are the e- carriers in complex I

A

FMN and Fe-S

234
Q

Draw Q structure

A

slide 16 of ETC

235
Q

Draw QH● structure

A

slide 16 ETC

236
Q

Draw QH2 structure

A

slide 16 ETC

237
Q

how is FADH2 similar to QH2

A

can both undergo single electron transfers (SET)

238
Q

NADH- coenzyme Q oxidoreductase is found in

A

complex I

239
Q

what reduces complex I and what oxidizes it

A

NADH reduces
CoQ is oxidizes

240
Q

final electron acceptor of oxidative phosphorylation

A

O2

241
Q

CoQ characteristics

A

lipid soluble e- carrier
moves within the lipid bilayer

242
Q

what process is the following below:
NADH + H+ + 1/2O2 —-> NAD+ + H2O

A

Electron Transport Chain

243
Q

In the presence of uncouplers energy is converted to

A

heat

244
Q

what are other sources of entry into ETC

A

Acyl-CoA DH
Glycerol-P-oxidase

245
Q

For ATP to be made what must be present in the matrix

A

ADP
Pi
H+

246
Q

malate-aspartate shuttle is used in what organs

A

the liver, kidney, and heart

247
Q

glycerophosphate shuttle is used more in what kind of organs

A

skeletal muscle and the brain

248
Q

name the shuttle that couples cytosolic oxidation of NADH with mitochondrial reduction of FAD

A

Glycerophosphate shuttle

249
Q

what is the net yield of ATP for 1 glucose molecule undergoing complete oxidation via gylcerophosphate shuttle?

A

30 ATP

250
Q

what is the net yield of ATP for 1 glucose molecule undergoing complete oxidation via malate-aspartate shuttle

A

32 ATP

251
Q

ROS are generated when

A

oxygen is only partially reduced

252
Q

what ROS serves as the precursor for other types of ROS

A

superoxide radical (O2-)

253
Q

what is the most potent oxygen radical

A

hydroxyl radical (OH-)

254
Q

how do we form hydroxyl radical

A

Fenton chemistry using oxidation of Fe2+ with the splitting of hydrogen peroxide ( H2O2)

255
Q

H2O2 + Fe2+ —> OH + OH- + Fe3+

what is this process called and what does it form

A

Fenton Chemistry
Forms hydroxyl radical

256
Q

In terms of ROS what is the function of antioxidants

A

destroy oxidative free radicals

257
Q

Superoxide Dismutase function

A

convert superoxide to hydrogen peroxide

258
Q

hydrogen peroxide is targeted by two enzymes for conversion of water what are they?

A

catalase
Glutathione Peroxidase

259
Q

what enzyme catalyzes this process

2O2- + 2H+ –> H2O2 + O2

A

superoxide dismutase

260
Q

where can we find superoxide dismutase

A

in the mitochondrial containing Mn

cytosol containing Cu and Zn

261
Q

what is known as the first line of defense against ROS

A

Superoxide Dismutase

262
Q

where can we find Glutathione

A

mitochondria

263
Q

where can we find GSH reductase

A

erythrocytes

264
Q

function of GSH peroxidase

A

eliminate hydrogen peroxides

265
Q

function of NADPH in terms of GSH

A

donates electrons to GSSG
regenerates GSH and NADP+

266
Q

function of GSH reductase

A

regenerate GSH
eliminate H2O2

267
Q

What enzyme involves the use of a heme where a radical cation is generated

A

catalase

268
Q

what is known for being generated as part of normal metabolism of oxygen

A

endogenous ROS

269
Q

what known for being generated from pollutants, tobacco,smoke, drugs, or radiation

A

exogenous ROS

270
Q

why do we care about oxidative stress

A

it can lead to a number of degenerative diseases associated with oxidative damage to mitochondria

271
Q

what TCA intermediate is known as the primer for FA, cholesterol syntehsis , and histone acetylation

A

citrate

272
Q

breakdown of citrate in the cytosol produces what to metabolites? via what enzyme?

A

OAA and acetyl CoA

ATP-citrate lyase

273
Q

function of citrate carrier

A

responsible for efflux of acetyl-CoA from mitochondria to cytosol in form of citrate

274
Q

what are the three modes of inhibition

A

complex inhibitors
ATP synthase inhibitors
Uncouplers

275
Q

why do we care about inhibitors of ETC

A

let us know what is happening in each complex in terms of mechanisms

276
Q

what are the inhibitors of NADH-UQ ( Complex I)

A

Rotenone
Amytal
Demerol

277
Q

how do rotenone, amytal, and demerol inhibit complex I?

A

prevent the reduction of CoQ by stopping oxidation of Fe-S clusters

no longer passes e- from complex I to CoQ

278
Q

What are the inhibitors of cytochrome c Oxidase ?

A

Cyanide
Azide
Carbon monoxide

279
Q

what does cyanide and azide both block

A

cytochrome a3 ( ferric form)

280
Q

what does carbon monoxide block

A

cytochrome a3 ( ferrous form)

281
Q

T/F all of the inhibitors of complex IV bined to the heme of Cyt a3

A

T

282
Q

name the inhibitor for ATP synthase

A

oligomycin

283
Q

function of oligomycin

A

blocks movement of protons through the F0

284
Q

where does oligomycin bind to and what it makes contact with

A

surface of the C10 ring making contact with two neighboring molecules

285
Q

How do uncouplers function

A

by obtaining protons in the IMM space and carry them to the matrix side allow for ATP synthase to be bypassed

286
Q

Name the inhibitor that are agents that disrupt the tight coupling between e- transport and ATP synthase

A

uncouplers

287
Q

give an example of an uncoupler

A

Dinitrophenol

288
Q

Draw glycoxylate cycle

A

slide 33

BICH 411 (4 decks)

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