Cellular Respiration

Cells, like all things, need energy to operate. CD players use batteries for energy, cells use adenosine triphosphate (ATP) for energy. Unlike CD players, cells can produce their own energy. People don't eat ATP, though. Their food consists mostly of proteins, lipids, and polysaccharides (sugars) which need to be broken down into ATP. There are three major stages in converting food into ATP: food breakdown, glycolysis, and the Kreb Cycle.

	Overview of Cellular Respiration Get a general picture of cellular respiration.
	Stage 1: Food Breakdown Before food can be converted into ATP, it must be broken down into simpler forms of sugar, lipid, or amino acids.
	Stage 2: Glycolysis The simple molecules from stage 1 must be converted into a intermediate product before it can be converted into ATP.
	Stage 3: Aerobic Respiration In this step, food is finally converted into ATP.
	Fermentation In the absence of oxygen, cells undergo fermentation to produce ATP.