Cell Integrity Flashcards
Where does oxidative phosphorylation occur?
MItochondria
Where is the bulk of ATP generated within the mitochondria?
Electron transport chain in the inner membrane
What are cristae?
Folds that project inwards
What is the role of cristae?
Increase the surface upon which oxidative phosphorylation can take place
What happens to NADH and FADH2 in the mitochondria?
They are reoxidised by molecular oxygen
What is the equation for the oxidation of NADH?
NADH + H+ + 1/2 O2 —> NAD+ & H2O
What is the equation for the oxidation of FADH2?
FADH2 + H+ + 1/2 O2 —> FAD &H2O
What membrane proteins are present in the ETC?
Complex I (NADH dehydrogenase) Complex II (succinate dehydrogenase) Complex III ( Q- cytochrome C oxioreductose) Complex IV (cytochrome C oxidase)
What are the mobile carriers present in the ETC?
Coenzyme Q (ubiquinone) Cytochrome C
What is the process of the electron transport chain?
Complexes I, II & IV accept e- and a proton (H+) from the aqueous solution.
As the e- pass through each of these complexes, a proton is pumped into the inter membrane space
What is succinate dehydrogenase?
- An enzyme of the TCA cycle
- sits in the inner mitochondrial membrane
- uses FAD as a cofactor
- can communicate directly with coenzyme Q
What happens when complex I is successfully bypassed?
Fewer H+ are pumped to the inter membrane space when FADH2 is reoxidised compared to NADH
FEWER ATP MOLECULES ARE GENERATED FROM THE REOXIDATION OF FADH2
What is the definition of a REDOX reaction?
Electron transfer reactions involving a reduced substrate (which donates e- & is oxidised) and an oxidised substrate (which accepts e- and becomes reduced)
What is the definition of a REDOX couple?
The substrate can exist in both oxidised & reduced forms
NAD+ & NADH
FAD & FADH2
Fe3+ & Fe 2+
1/2 O2 & H2O
What is the definition of a REDOX potential?
The ability of a REDOX couple to accept/donate e-
How can the standard redox potentials (Eo) be measured?
Using a hydrogen electrode as a reference experimentally
(-)ve Eo
The redox couple has a tendency to donate e- and has more reducing power than H
NAD+/ NADH Eo= -0.32V
(+)ve Eo
The redox couple has a tendency to accept e- and therefore has more oxidant power than H
Fe3+/ Fe2+ Eo= + 0.82 V
What happens as the e- progress along the ETC?
They lose energy
The transfer of e- from one complex to another is energetically favourable
What is ATP synthase?
A multi Eric enzyme consisting of a membrane bound part Fo and F1 part which projects into the matrix space
Rotation of the enzyme drives transition states with alternating affinities for ATP & ADP
How does ATP synthase work?
Conformational E flows from the catalytic subunit into the bound ADP and Pi to promote the formation of ATP
CHEMICAL Energy
What the direction of proton flow through ATP synthase determine?
Determines ATP synthesis Vs ATP hydrolysis
ATP synthesis: H+ into the matrix
ATP hydrolysis: H+ out of the matrix into inter membrane space
What is the oxygen electrode?
A device that measures O2 conc in a solution within a small chamber
What are the steps taken for an Oxygen Electrode?
- A small voltage of 0.6V is applied between the anode(+) and the cathode(-)
- O2 diffuses through the Teflon membrane & is reduced to H2O at the Pt cathode
O2 + 4H+ 4e- —> 2H2O - The circuit is completed at the Ag anode which is slowly oxidised to AgCl by the KCl electrolyte
4Ag+ + 4Cl- —> AgCl + 4 e- - Current is proportional to the O2 conc
