Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
66 Cards in this Set
- Front
- Back
|
what is the name of complex I?
|
NADH-CoQ oxido-reductase
|
|
|
what are its prosthetic groups
|
FMN and 9 Fe-S centers
|
|
|
what are the features of an iron-sulfur center
|
it's a non heme iron bound to inorganic sulfur and S from cysteine side chains
|
|
|
what accepts electrons from Fe-S centers of complex I
|
coenzyme Q (aka ubiquinone)
|
|
|
what are the features of ubiquinone
|
lipid soluble - only non protein component of ox-phos
can form free radicals |
|
|
what is the name of complex III
|
CoQ - Cytochrome C oxido-reductase
|
|
|
what are the prosthetic groups of complex III
|
cyt b (2 hemes)
cyt c1 (1heme) one Fe-S center |
|
|
what is a cytochrome
|
small heme containing protein undergoing ox-phos
|
|
|
when is cytochrome oxidized or reduced?
|
heme Fe+++ is oxidized
Fe++ is reduced |
|
|
how many cytochromes in ox-phos, where are they?
|
2 in complex II
cyt c 2 in complex IV |
|
|
what is the heme Fe bound to in cyt a3?
|
6 binding positions
4 bound to porphyrin ring 5th bound to histidine 6th bound to O2 when Fe++ (reduced) |
|
|
which cytochromes have all 6 positions bound to Fe? what are they bound to?
|
6 binding positions
4 bound to porphyrin ring 5th bound to histidine 6th position in cyt a,b,c, c1 bound to methionine (Met) |
|
|
the reducing (standard potential) of cytochrome influenced by...
|
the polypeptide chain around it
|
|
|
what reduces complex IV
|
cytochrome C
|
|
|
features of cyt c
|
one polypeptide chaing with a heme
water soluble high positive charge on the surface helps it bind to complex II and IV (electrostatic binding) |
|
|
where is cyt c located?
|
inermembrane space
|
|
|
which molecule of electron transport chain also a trigger for apoptosis
|
cyt c
|
|
|
name of complex IV
|
cytochrome c oxidase
|
|
|
what are the prosthetic groups of complex IV
|
cyt a
cyt a3 2 copper ions |
|
|
what does cytochrome c oxidase reduce?
|
transfers 4e- to oxygen --> water
|
|
|
what is the name of complex II
|
succinate dehydrogenase (from TCA)
|
|
|
what are the prosthetic groups of complex II?
|
FAD coenzyme
one Fe-S center |
|
|
what is the cascade of electrons in complex II?
|
FAD --> FADH2 --> Fe-S --> CoQ
|
|
|
what does CN inhibit? where does it bind?
|
CN binds to 6th Fe position of cyt a3, keeps it in oxidized state - Complex IV
|
|
|
what are the effects of CN on ETC?
|
all components up to IV are fully reduced
stops ETC and ATP production |
|
|
where does Antimycin A inhibit?
|
binds to cyt b in reduced state - Complex III
|
|
|
how does antimycin A affect ETC?
|
I, CoQ, II are fully reduced
cyt c, IV are fully oxidized stops ETC, no ATP made |
|
|
where does retenone inhibit?
|
retenone inhibits Complex I, NADH can't be oxidized but FADH2 can still enter through Complex II
|
|
|
how do you treat cyanide poisoning?
|
convert 25% heme to MetHb by oxidizing it with amyl nitrate and then sodium nitrate
then inject thiosulfate to convert to thiocyanate which is excreted by kidneys |
|
|
what points in TCA make NADH?
|
1. alphaketogluterate --> succinyl CoA
2. isocitrate --> alphaketogluterate 3. malate --> AOA |
|
|
where is the NADH binding portion of complex I?
|
matrix - site of TCA
|
|
|
where is pH more basic and potential more negative?
|
matrix
|
|
|
what does "respiratory control" mean?
|
rate of electron transport is limited by energy needs - the ratio of ADP/ATP
|
|
|
what is ETC limited by when its uncoupled?
|
availability of NADH, succinate (FADH2), O2
|
|
|
what does 2,4 dinitrophenol inhibit?
|
it's an uncoupler which stops ATP synthesis and keeps TCA going at high rate by dissipating H+ gradient
|
|
|
what parts of ATP synthase are part of inner membrane?
|
F0: a = proton pathway
b=stator c=rotator |
|
|
what parts of ATP synthase stick out into matrix?
|
F1: gamma= rotating shaft that interacts with beta globules
globular head of alpha and beta chains delta chain that fixes head with stator |
|
|
how many ATP made with 360 degree rotation of gamma?
|
3
|
|
|
what does oligomycin bind to and inhibit?
|
binds to F0 and blocks proton pathway, ATP can't be made and proton gradient builds up which stops TCA
|
|
|
how many mtDNA in a cell?
|
10-200 mitochondria per cell with 2-50 circles of mtDNA per mitochondria
|
|
|
what does mtDNA look like?
|
double stranded
circular no introns |
|
|
what does mtDNA code for?
|
2 ribosomal RNAs
22tRNAs 13 polypeptides of ETC: complex I, III, IV, V |
|
|
how are mitochondrial proteins targeted?
|
amino terminal basic amphiphilic helix
positive charge on one side hydrophobic on another side |
|
|
what does signal sequence of mitochondria bound proteins bind to?
|
acidic receptor and protein conducting channel
TOM: transport outer membrane |
|
|
what is TIM?
|
transport inner membrane - has an ATP driven translocase motor
|
|
|
how do molecules get across inner membrane?
|
family of transporters, carry one thing in, another thing out
all have 6 transmembrane helices |
|
|
what does ANC (ANT) do? how?
|
adenine nucleotide carrier - brings ADP into matrix and ATP out. Pi has a different transporter
|
|
|
what does atractyloside inhibit?
|
inhibits ANC - adenine nucleotide carrier - stops ATP formation and ETC b/c the H gradient gets too high
|
|
|
how are uncoupling proteins a type of inner mitochondrial membrane transporter?
|
H+ into matrix
OH- out of matrix |
|
|
how does NADH from glycolysis (cytoplasm) get to ETC?
|
1. malate-aspartate shuttle
2. alpha-glycerol phosphate shuttle |
|
|
what is required for malate-aspartate shuttle to work?
|
high NADH in the cytoplasm
|
|
|
how does malate-aspartate shuttle work?
|
in cytoplasm NADH reduces AOA ->malate
malate crosses into matrix in matrix malate ->AOA +NADH |
|
|
what enzyme converts b/w malate and AOA
|
cytosolic and mitochondrial malate dehydrogenase
|
|
|
how does AOA get out of mitochondria in malate-aspartate shuttle?
|
AOA->aspartate by mitochondrial glutamic-oxaloacetic transaminase
aspartate crosses mitochondrial membranes aspartate->AOA by cytosolic glutamate-oxaloacetic transaminase |
|
|
what 2 transporters are needed for malate-aspartate shuttle?
|
1. glutamate-aspartate transporter
2. malate-alphaketogluterate transporter |
|
|
how does a-glycerol phosphate shuttle work?
|
1. NADH from glycolysis transfers e- to G3P
2. G3P reacts with FMN of G3P dehydrogenase complex in mitochondrial membrane 3. FAD of complex transfers e- to CoQ (acts like complex II, get 2ATP) |
|
|
how are ROS generated?
|
when TCA slows down - partially reduced CoQ = semiquinone anion
this donates 1e- to oxygen generating superoxide anion |
|
|
what are 3 types of ROS
|
superoxide anion: O2`-
H2O2 OH- |
|
|
function of superoxide dismutase
|
superoxide anion --> H2O2
|
|
|
function of glutathione peroxidase
where is it found? |
H2O2 --> O2 +H20
located in cytoplasm and mitochondria |
|
|
function of catalase
where is it found? |
H2O2 --> O2 +H20
located in peroxisomes |
|
|
what is mutated to cause ALS?
|
superoxide dismutase - ROS damage neurons
|
|
|
definition of homoplasmy and heteroplasmy
|
homoplasmy - all mtDNA in a cell are the same
heteroplasmy - mix of mutant and normal mtDNA in cell |
|
|
what does severity of mitochondrial disease depend on?
|
proportion of mutant mtDNA (heteroplasmy)
|
|
|
what builds up when ox-phos not working properly (mitochondrial diseases)
|
lactic acid
|
|
|
where do mutations occur in mitochondrial diseases?
|
either mtDNA or nuclear DNA
|
