Chapter 10: Energy Carriers

Oxidation – Reduction

  • Oxidation is the loss of electrons
  • Reduction is the gain of electrons

Use the mnemonic, “OILRIG”, to remember
Oxidation – reduction (redox) reactions are very important for living organisms as energy can be transferred very efficiently from one form to another – i.e. chemical energy to heat, kinetic, sound energy

Energy carriers take part directly in metabolic reactions by:

  • Gaining high energy electrons (reduction)
  • Losing electrons that have given up their energy (oxidation)

ATP (adenosine triphosphate)
Is the ‘energy currency’ of the cell

It is composed of:

  • Adenine
  • Ribose
  • Three phosphates

NAD (nicotinamide adenine dinucleotide)

  • Electron carrier used in aerobic respiration
  • Picks up energised electrons (reduction) after a bond is broken and carries them to the electron transport chain where they release their energy in an enzyme-controlled environment to produce ATP

NAD+ + 2e + H+ → NADH

NADP (nicotinamide adenine dinucleotide phosphate)

  • Electron carrier used in photosynthesis
  • Picks up energised electrons (reduction) that originated from chlorophyll molecules that were hit by light and transfers them along with protons to the dark stage in order that CO2 may be reduced (addition of H+ and e) to form glucose

NADP+ + 2e → NADP + H+ → NADPH