metabolism, energy, and enzymes - redox reactions and electron carriers

redox reactions

• are COUPLED reactions that play a role in flow of energy in biological systems.. transfer of electrons from one substance to another

  • LEO RA and GER OA

• most IMPORTANT redox reaction in eukaryotic cells occurs when glucose is oxidized to form carbon dioxide and water CELLULAR RESPIRATION

energy levels and electrons

• electrons that pass from one atom to another carry energy

  • high energy level - reduced form of a molecule

  • low energy level - oxidized form of a molecule

two important electron carriers

the coenzymes

NAD+ and FAD

• they are recycled, flip flopping between reduced and oxidized forms and it picks up and drops off electrons

NAD+

• nicotinamide adenine dinucleotide

• oxidized NAD+ reduced NADH

• becomes reduced by:

  • NAD+ gains 2 e from 2 H atoms acquires 2 e and H+ to become reduced to NADH

  • 1 H+ released into solution, cell’s cytosol

FAD

• flavin adenine dinucleotide

• oxidized FAD reduced FAH2

• becomes reduced by:

  • FAD gain 2 e from 2 H atom to become reduced

oxidation of food during cellular respiration

• uses enzymes DEHYDROGENASES that transfer high energy electrons from food/glucose to energy carriers, reducing them ex. NAD+ to NADH + H+