Cellular Respiration is the chemical process that ALL organisms use to release energy from their food. The process occurs in special sausage shaped structures, found in cells, called mitochondria. The more energy a cell needs to produce the more mitochondria it will have. (ex. heart cells or muscle cells have more mitochondria to support the work needed for the body to function).
We breathe in oxygen because it is one of the necessary reactants for respiration. The energy we need is provided by our food, but we also learn about respiration using one particular energy source, glucose, as a reactant.
When respiration occurs, the products are carbon dioxide (which we breathe out), water, heat, and ATP. ATP is the molecule that stores the energy released from our food and is then used for any energy requiring activities in our bodies.
As with photosynthesis, many enzymes are involved in speeding up cell respiration.
Oxygen + Glucose Carbon Dioxide + Water + ATP
6O2 + C6H12O6 6CO2 + 6H2O +ATP
Picture of some Meerkats and an Animal Cell (Prentice Hall 2008)
Types of Respiration
1. We need oxygen to live and so we do Aerobic Respiration (meaning respiration that needs oxygen). Aerobic respiration makes a large number of ATP molecules and is most often used by your body when oxygen is available.
Picture of the Inside of a Mitochondrion
Aerobic Respiration Equation
Oxygen + Glucose Carbon Dioxide +Water+ 36ATP +Heat
2. However our muscles are capable of doing respiration without oxygen for short periods of time. Respiration without oxygen is called Anaerobic Respiration (also called Fermentation).
Anaerobic Respiration Equation
Glucose Carbon Dioxide + Water + 2ATP + Heat +Lactic Acid
A. Plants or yeast do Anaerobic Respiration. One of the by-products is alcohol (ethanol) which is how alcoholic drinks are made.
B. When animals do Anaerobic Respiration the by-product is Lactic Acid which causes muscle cramps.
We cannot survive without oxygen for two reasons:
1. The by-product of fermentation is lactic acid (causing muscle cramps) which is also toxic to brain cells. Because of this, we can only live for a few minutes without oxygen before brain damage occurs.
2. Anaerobic Respiration (fermentation) only produces TWO ATPs per glucose which is not enough energy for us to survive.