Cellular Respiration

Cellular Respiration In a Nutshell

Overall • Food  ATP  Glucose + O2 +ADP + P  CO2 + H2O + ATP

2 Types Aerobic Anaerobic Without oxygen Produces a little ATP • With oxygen • Produces a lot of ATP

Aerobic Respiration • Glycolysis • Krebs Cycle • Oxidative Phosphorylation

Glycolysis • Occurs in all cells ever studied. • No oxygen required, no mitochondria • Probably evolved in the earliest forms of life

Glycolysis • Sugar is split into pyruvate • 2 ATP are made • Some electrons passed to NAD+ to form NADH

Krebs Cycle • If oxygen present, the pyruvate heads into the Mitochondria • Series of enzyme-catalyzed reactions

Krebs Cycle • Rest of sugar broken into Carbon Dioxide • 2 more ATP made • Some electrons donated to NAD+ to form NADH (and another electron carrier)

So Far • Some ATP made (4), but we have a lot of electron carriers (NADH and others) which possess energy

Oxidative Phosphorylation • LOTS of ATP made (about 34) as electrons are passed from NADH through a series of proteins to O2 to form water

With No Oxygen • No Oxidative phosphorylation • No Krebs Cycle • Only source of ATP is glycolysis No O2, No problem Well for like a minute

BUT… • Glycolysis needs NAD+, and with no Ox. Phos the cell runs out of NAD+ • So fermentation must occur to remake NAD+ and allow glycolysis to continue

Review • Aerobic

Review • Anerobic

Cellular Respiration