The Respiratory Chain and Oxidative Phosphorylation (Chapter 13) Flashcards
What Processes is the Mitochondria involved in?
- Fatty Acid Oxidation
- Citric Acid Cycle
- Urea Cycle
- Amino Acid Degradation
- Oxidative Phosphorylation
1) What enzymes are found on Inner Membrane?
2) What lipid do we find in the inner membrane?
1)
- Complex I-IV
- ATP Synthase
- Membrane transporters
2) Cardiolipin
What enzymes are found on the outer membrane?
Acetyl CoA synthesase
Glycerophosphate Acyl transferase
What is Oxidative Phosphorylation?
It is when we couple Electron flow with the pumping of protons, thus liberated free energy is trapped as high energy phosphates.
1) What is the Redox Span from NADH -> O2
2) Path taken for electron
1) 1.1V.
2) From Complex I -> Compex III to Complex IV then to oxygen. Reducing it form H20.
At which Complexes are protons pumped into the intermembrane space?
Complex I, III, III
When is Succinate-Q- Reductase (complex II) used?
For substrates that have a more positive redox potential than Nad+/NADH
1) Which Complexes have Flavoproteins in them?
2) What is their purpose?
1) Complex I and II have flavoproteins FMN and FAD.
2) The purpose is to be able to:
- Be reduced in Rxns involving transfer of 2 electrons
- can accept an electron as well, to form the semiquinone.
1) Which Complexes have Fe-S proteins in them?
2) What is the formation of this Fe-S protein?
3) Purpose?
1) Complexes 1,2,3 all have Fe-S proteins.
2) consists of one, two or four Fe joint to inorganic sulphur via cystein group to protein.
3) They can transfer a single electron.
What consists of Complex I?
1) FMN
2) Fe-S proteins
What does Complex I do?
It takes 2 electrons from NADH, and pumps one H+ for each electron passing.
Thus in total 4H+ is pumped here.
What does Complex II consist of?
1) FAD
2) Fe-S Proteins
1) How is FADH2 formed?
2) How many H+ pumped at complex II?
1) FADH2 is formed by the conversion of: Succinate to Fumarate.
2) 4H+
Which complexes provide electron to Coenzyme Q?
I and II.
What does Complex III do?
Takes electrons from Co-enzyme Q and transfers them to Cytochrome C,
It couples the movement of these electrons to the pumping of 2H+ into the intermembrane space.
What does Complex III consist off?
- Cytochrome C1
- Cytochrome bL and bH
- Rieske Fe-S (special because it is linked to histidine not cysteine).
Explain the Q-cycle:
1 electron goes to cytochrome C via the Rieske Fe-S then to cytochrome C1
The other electron goes back to Q via cytochrome bL then bH to form Semiquinone.
Leads to pumping of 2H+
How is the Semiquinone made into a quinone?
Second cycle of Co-enzyme Q donates one electron to the Semiquinone to form quinone.
How many electrons can Co-enzyme Q carry?
2 electrons
How many electrons can cytochrome C carry?
1
What does Complex IV consist of?
Consists of:
- Cu
- Heme a & a3.
1)What is the name of Complex IV?
It is Cytochrome Oxidase.
Pathway of Electrons in Complex IV
Cu–>heme a –> heme a3 –> cu –> then FINALLY TO oxygen.
Oxygen remains tightly bound to complex IV, until it’s finally reduced.
This prevents release of potentially damaging intermediates forming.
How many H+ removed from matrix at Complex IV?
8H+ removed from matrix.
4H+ used to form water.
4H+ pumped into the intermembrane space.
What is the Chemiosmotic Theory?
There is a proton gradient, which generates a proton motive force.
This drives the mechanism for ATP synthesis.
Equation for ATP Synthaeses?
ADP + Pi –> ATP
Structure of ATP Syntheases?
F1:
- Protrudes into the matrix.
- Consists of Alpha + Beta Subunits.
F0:
- spans the membrane.
- consists of disks of c-proteins.
How does ATP syntheases work?
- B subunit bind to ADP.
- Gamma Axle rotates due to protons entering C-proteins.
- This squeezes B subunit causing a conformational change which leads to formation and release of ATP.
How many ATP molecules are created per revolution?
3.
What is P/O Ratio?
The amount of ATP produced per oxygen atom reduced by the respiratory chain.
What is P/O ratio of:
NADH-linked Substrate
FADH2-linked Substrate
- 7
1. 6
What is State 1 in Respiratory control?
Avaliability ADP and Substrate level
What is State 2 in Respiratory Control?
Availability of Substrate ONLY
What is State 3 in Respiratory control?
The ETC capacity?
What is State 4 in Respiratory control?
Availability of ADP alone.
What is State 5 in Respiratory control
Availability of oxygen
What state are most cells in?
State 4
During exersise which state of respiratory control
3/5
What happens to the free energy that is not used?
It is released as heat. Important because it ensures unidirectional flow of ATP
What do barbituates do?
Affect complex I eg: -Amobarbital -Rotenone -Piercidin A
Which poisons affect Complex II?
Malonate
Which poisons affect complex III
Actimycin A + Dimercaprol
Which poisons affect complex IV?
Cyanide
Carbon monoxide
H2S
What blocks flow of protons through ATP Synthaese?
Oligomycin
What do uncouplers do? give an example?
Oxidation becomes uncoupled from phosphorylation.
2,4 Dinitrophenol is an uncoupler.
