PACKET #29CHAPTER #9

Anaerobic RespirationCellular Respiration Without

Oxygen

Anaerobic Respiration I

For most animal and plant cells, glycolysis is only a prelude to the final stages of the breakdown of food molecules.

Normally, pyruvate is transported to the mitochondria and is converted into CO2 plus ACoA. Ultimately to more CO2, during the Kreb’s Cycle, and

H2O, using oxygen, during oxidative phosphorylation

Anaerobic Respiration II

For organisms that do not utilize molecular oxygen, and are able to grow and divide without it, glycolysis is the principle source of a cell’s ATP.

If no oxygen is available, the pyruvates formed at the end of glycolysis do not enter the Kreb’s Cycle but follow one of a number of anaerobic pathways that are often referred to as fermentation.

Anaerobic Respiration III

The pathways frequently use up 2 H+ and NAD+ via oxidation—allowing the NAD+ to be used again in glycolysis.

Lactate Acid Fermentation Alcoholic Fermentation

Glucose + 2P + 2ADP 2 lactate + 2 ATP + 2 H2O A small amount of energy is

released Occurs in muscles during

intense exercise. Increase in lactate results in

cramps.Two Steps

Glycolysis NAD+ Regeneration

This stage produces NAD+ and lactate.

Glucose + 2P + 2ADP 2 ethanol + 2ATP + 2CO2 A small amount of energy is

released Occurs in anaerobic bacteria

and yeasts Useful in the production of

alcoholic beverages and bread.Three Steps

Glycolysis Pyruvate to acetaldehyde NAD+ Regeneration

Fermentation