Redox Flashcards
What are redox reactions?
Redox reactions are defined as electron transfer reactions involving a reduced substrate (which donates electrons and therefore becomes oxidised) and an oxidised substrate (or oxidant) which accepts electrons and becomes reduced in the process.
What is a redox couple?
A substrate that can exist in both oxidized and reduced forms is known as a redox couple, e.g. NAD+/ NADH or FAD / FADH2
What is redox potential?
The ability of a redox couple to accept or donate electrons is known as the reduction potential orredox potential.
What does the standard redox potential use as a reference?
The ability of hydrogen to reduce/oxidise.
What does a negative E0 imply?
A negative E0implies that the redox couple has a tendency to donate electrons and therefore has more reducing power than hydrogen.
What does a positive E0 imply?
A positive E0implies that the redox couple has a tendency to accept electrons and therefore has more oxidising power than hydrogen.
What happens to electrons as they progress along the electron transport chain?
The transfer of electrons from one complex to another is energetically favourable and as they progress along the chain, the electrons lose energy.
What is the oxygen electrode?
The oxygen electrode is a device that measures the oxygen concentration in a solution housed within a small chamber.
What is the oxygen electrode made of?
The base of the chamber is formed by a Teflon membrane permeable to oxygen. Underneath this membrane, is a compartment containing two electrodes, a Platinum (Pt) cathode and a silver (Ag) anode.
How does an oxygen electrode work?
A small voltage of around 0.6 volts is applied between the anode (+) and cathode (-).
Oxygen diffuses through the teflon membrane and is reduced to water at the platinum cathode.
The circuit is completed at the silver anode, which is slowly oxidised to AgCl by the KCl electrolyte.
The resulting current is therefore proportional to the oxygen concentration in the sample chamber.
How can we use the oxygen electrode to study the ETC?
The first step is to prepare a suspension of mitochondria from a tissue and place them into the chamber of the oxygen electrode.
If the oxygen consumption of the suspension is then monitored for a set time period, the effects of various substrates and inhibitors on the electron transport chain can be determined.
