Oxidative Phosphorylation Flashcards
In which stage of metabolism does oxidative phosphorylation take place?
Third Stage
Also known as “tertiary metabolism”
What is the goal of oxidative phosphorylation?
Conversion of food energy to ATP
Where does oxidative phosphorylation take place in the eukaryotes?
Inner mitochondrial membrane
What is the major source of energy in a cell?
Oxidative phosphorylation
What provides energy to carry out oxidative phosphorylation? And what is this energy used for?
- Energy is provided by the wide difference between the redox potentials of the electron donor and electron acceptor (reaction is exergonic).
- Most of this energy is used to create a proton gradient which helps in the synthesis of ATP through ATP synthase.
Why is the respiratory chain highly exergonic?
Due to the wide difference in redox potentials of electron donor and acceptor.
Why is the Electron Transport Chain (ETC) a multi-step redox reaction?
- It involves the oxidation of NADH and FADH2 to give electrons that reduce O2 to water.
- Simultaneously, the enzymes create a proton gradient that can drive ATP synthesis.
What drives the ATP synthase?
Proton gradient
Which is the final electron acceptor?
Oxygen
What is the final stage of aerobic respiration?
Oxidative phosphorylation
What are the 4 main complexes of the ETC?
- Complex 1: NADH dehydrogenase/ NADH coenzyme Q reductase
- Complex 2: Succinate dehydrogenase/ Succinate coenzyme Q reductase
- Complex 3: Coenzyme Q- cytochrome C oxidoreductase/ Cytochrome bc1 complex
- Complex 4: Cytochrome C oxidase
Why does the ETC take place in the inner membrane of the mitochondria?
- Because it is rich in proteins.
- It processes specialised particles that are the centre of ATP production.
- It is semi-permeable.
What particles is the mitochondrial inner membrane impermeable to?
ATP, ADP, Na+, K+, H+
What are the two processes that take place in oxidative phosphorylation?
- The Electron Chain Transport
- ATP synthesis (Phosphorylation)
Why does the mitochondrial matrix get more alkaline and negatively charged during O.P?
The energy from the transfer of electrons charges the complexes 1, 3 and 4, causing them to pump H+ ions from the matrix to the inner membrane space, making the matrix more alkaline.
What is the Chemical Coupling Hypothesis?
Transfer of electrons in the ETC leads to the formation of an intermediate with high energy covalent bonds which forms the precursor to ATP synthesis.
What is the Chemi-Osmotic Theory?
Transfer of electrons from one complex to another energises the pumping of hydrogen protons to a inner membrane space, creating an electrochemical gradient. This proton gradient drives ATP synthesis.
How can ATP production be supressed?
- Uncoupling of oxidation and phosphorylation.
- Inhibiting the transfer of electrons in the ETC.
How do uncouplers work?
They uncouple oxidation and phosphorylation such that the ETC and ATP synthase operate well independently but do not work together to synthesise ATP.
Give examples of synthetic uncouplers.
- 2,4-dinitrophenol
- Valinomycin
- Gramicidin
Give example of physiological uncouplers.
- Thyroxine
- Thermogenins (in brown adipose tissue)
Give examples of Site 1 inhibitors.
- Rotenone
- Alkyl Guanines
- Barbiturates
- Actinomycin
How is naphthoquinone poisonous?
It is a Site 2 inhibitor. It inhibits the transfer of electrons from Cytochrome bc1 complex to cytochrom c.
Give examples of Site 3 inhibitors.
- Cyanide
- CO
- H2S
How is cyanide poisonous?
It inhibits the cytochrome c by binding with iron ions, and inhibiting transfer of electrons.
How is CO poisonous?
- High affinity for hemoglobin, and stabilises its R form.
- Inhibits cytochrome c by binding with it directly and preventing O2 attachment.
