Week 1- ATP production Flashcards
Where does the Krebs cycle take place
The mitochondrial matrix
Where does oxidative phosphorylation take place
Mitochondrial christae
What are the 2 equations for oxidative phosphorylation
NADH + H^+ + 0.5 O2 > NAD+ + H2O delta g= -223 kJ/mol
FADH2 + 0.5O2 > FAD+ + H2O delta g= -170 kJ/mol
Where are NAD and FAD+ reoxidised?
Christae
What evidence is there that mitochondria arose from prokaryotes?
Have own protein synthesis machinery
Start transcription with fMet instead of Met like eukaryotes
Have own genome of circular DNA
Only arise from pre existing mitochondria
Antibiotics that stop bacterial protein synthesis do the same in mitochondria but not in eukaryotes
Describe the events of the ETC
- NADH dehydrogenase complex has higher affinity for electrons than NADH so electrons are released
- 2 electrons at a time are carried via ubiquinone (coenzyme Q) to the cytochrome bc1 complex
- 1 electron at a time is carried via cytochrome C to the cytochrome oxidase complex
- Once there are 4 electrons at the cytochrome oxidase complex they combine with hydrogen and oxygen to form water
Energy released from the flow of electrons is used to pump H+ across the membrane
What is a redox couple?
A couple that can exist in both the reduced and oxidized states
What is a reduction potential?
The ability of a redox couple to donate or accept a pair of electrons
Negative= donates Positive= accepts
Describe the structure of ATP synthase
F1 unit: membrane bound, has a rotor that protons flow through
F0 unit: protides into cell, conformational change causes ADP to be formed from ADP+ Pi
ATP synthase can work in reverse if there is excess ATP in the cell it is hydrolysed to ADP+Pi (this time the rotor spins in reverse)
How is oxygen consumption experimentally measured?
An electrode is used and the current is directly proportional to the oxygen consumed because at the cathode O2 + 4 electrons + 2H+ > 2H2O
Mitochondria can be suspended in solution and current measured, then inhibitors/activators added to see what changes
What factor most importantly affects oxygen consumption?
How much ADP+Pi is available
How does dinitrophenol work?
It carries protons across the membrane, reducing the need for the energy released by the ETC and greatly increasing metabolic rate. Used to be used in slimming meds but small difference in dose between effective and toxic meant it was made illegal
How does the metabolic poison rotenone work?
Inhibits complex 1 so no electrons can pass onto co Q
How does the metabolic poison azide work?
Inhibits complex 3
How does the metabolic poison cyanide work?
Inhibits complex 3
