Mitochondrial respiratory chain Flashcards
Which membrane of mitochondria is most permeable?
Where is the electron transport chain found?
Inner > Outer
Inner
Name and describe complex 1 in the ETC.
NADH Dehydrogenase
MOST ATC GENERATED FROM E- ACCEPTANCE HERE!
Acceptor of electrons from NADH
Firstly by FMN–> FMNH2 which then passes electrons to QH2 (Energy is harnaced from movement of e- through membrane proteins to pump H+ across mitochondria)
Subsequent transfer of e- to a series of iron-sulphur clusters
4H+ pumped into intramembranal space from matrix (endergenic)
NADH + H+ +Q –> NAD+ + QH2
(H+ + Q–> QH2 is highly exergenic!)
Name and describe complex 2 in the ETC.
FADH2 Dehydogenase
DOESNT PUMP H+ !
E- from FADH2 pass to complex 2
Succinate to fumerate as Q to QH2
Name and describe complex 3 and 4 in the ETC.
Complex 3: Cytochrome bc1
4H+ pumped through
QH2 accepted by 3
Complex 4: Cytochrom oxidase
2H+ pumped through
1/2O2 + 2H+ –> H20
State the role of the G3P shuttle in the act of dehydrogenation.
G3P Shuttle acts as a substrate for mitochondrial dehydrogenase passing e- to Q/
State the three systems involved in synthesis of ATP within in the inner mitochondrial memebrane
State the equation for ATP synthesis
- Transport ADP + Pi into the matrix
- Synthesise ATP
- Transport ATP into the cytosol
ADP(3-) + Pi(2-) + H(+) –>/
Consider Adenine nucleotide transferase. How does exhange occur and what inhbits it?
It is an antiport channel with ADP(3-) being transported into the matrix and ATP(4-) being transported into the intramembranal space
(3-) exchange for (4-) is favoured by proton pump because complexes are pumping out H+ ions into intermembranal space
Atractyloside is a specific inhibitor of ANT
Consider Phosphate translocase.
It is a symport channel with both H2PO4 and H+ being transported from the intramembranal space to the matrix
Considered electro-neutral transport
Essential for oxidative phosphorylation and synthesis of ATP
(favoured by the transmembrane H+ gradient)
Brings in Pi into matric to make ADP
Outline the general structure of ATP Synthase
An F-type ATPase (with two functional groups):
F0: an oligomycin-sensitive proton channel
F1: an ATP synthase
Consider ATP Synthase. Describe the f groups
F0 comprises three different types of subunit: a,b and c
Forms a complex of 13-15 subunits
Subunuts c1-10 arranged in a circle
F1 comprises five different types of subunit: alpha3, beta3, gamma, δ and ε.
There form a complex of 9 subunuts.
THE THREE B-SUBUNITS have CATALYTICS SITES FOR ATP SYNTHESIS
Describe the theory of rotational catalysis including an explanation of the beta, delta and epsilon subunits
Beta-subunits are arranged alternatively with alpha-subunits like segments of an orange
(form knob held by stalk of the gamma and epsilon subunits)
The gamma unit rotates!
delta-subnunit interacts with the two beta-subunits of F0
3 b-sununits take it in turn to catalyse the synthesis of ATP
Any given b-subunit starts in a conformation for binding ADP and Pi
Then changes conformation so the active site now binds the product ATP tightly
Then changes conformation to give the active site a very low affinity for ATP (B-empty conformation) so ATP is released
Summarise the energy changes that occur across the mitochondrial membrane
The highly exergonic reaction :
NADH + H+ +1/2O2 –> NAH+ + H2O
is coupled to the movement of h+ across the inner membrane
Electrochemical energy generated represents temporary conservation of the energy of e- transfer (benerated by the seperation of charge and difference in proton conc)
Protons flow spontaneously down their electrochemical gradient releasing energy available to do work
How many ATP molecules generated by glycolysis when the G-3-P and malate-aspartate shuttle are used respectively?
3
5
How many ATP molecules generated by pyruvate oxidation (2 per 1 glucose)?
5
How many ATP molecules generated by acetyl-coA oxidation in citric acid cycle?
20
