Respiration

Cellular

You eat food to get energy…..how does this

work? By a process called……

Plants make their food, so to get energy from the food they produce they also use

a process called …..

Cellular

Respiration

1st step – Glycolysis (using Latin P&S, glycolysis means – loosening of glucose)

The process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid.

Takes place in the cytoplasm Creates 2 ATP

2nd step – the Krebs Cycle

Pyruvic acid is broken down in to carbon dioxide in a series of energy extracting reactions.

Creates NADH and FADH2 (energy carriers, full batteries)

Takes place in the mitochondria Creates 2 ATP

3rd step – Electron Transport Chain

Uses the energy stored in NADH and FADH2 to create ATP

Takes place in the mitochondria Creates 32 ATP

ATP

Big Picture Glycolysis + the Krebs Cycle + Electron Transport

Chain

= CELLULAR RESPIRATION

6O2 + C6H12O6 6CO2 + 6H20 + energyo This equation is the OPPOSITE of

photosynthesis

Cellular Respiration only works if

you have oxygen (which we

breathe in), but sometimes your

body can’t get oxygen quickly

enough to do cellular respiration

… what happens then?

1st step – Glycolysis Glycolysis does NOT require oxygen,

so the first step is the same.

2nd step – Alcoholic Fermentation Yeasts and a few other

microorganisms take the two molecules of pyruvic acid produced in glycolysis and convert it to alcohol, carbon dioxide and NAD+

Pyruvic acid + NADH alcohol + CO2 + NAD+

Alcoholic fermentation of yeast is what causes bread to rise. When yeast in the dough runs out of oxygen it begins producing carbon dioxide which forms the air spaces you see in a slice of bread. The small amount of alcohol produced in the dough evaporates.

OR 2nd step – Lactic Acid Fermentation In many cells, the pyruvic acid from

glycolysis is converted to lactic acid. Pyruvic acid + NADH Lactic Acid + NAD+

When you exercise vigorously by running, swimming or riding a bike, your large muscles quickly run out of enough oxygen to do cellular respiration. Instead your muscle cells start doing lactic acid fermentation to make ATP (energy). The build up of lactic acid causes a painful burning sensation.

The only way to get rid of this lactic acid is through a process that requires oxygen. This is why you breathe harder after physical activity.