Cellular RespirationIn a Nutshell

Overall

Food ATP

Glucose + O2 + ADP + P CO2 + H2O + ATP

2 Types

AerobicWith oxygenProduces a

lot of ATP

AnaerobicWithout

oxygenProduces a

little ATP

Aerobic Respiration

GlycolysisKrebs CycleOxidative

Phosphorylation

Glycolysis

Occurs in all cells ever studied.No oxygen required, no

mitochondriaProbably evolved in the

earliest forms of life

GlycolysisSugar is split into pyruvate2 ATP are madeSome 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 madeSome 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