Cellular Respiration
When you eat, you digest your food and the nutrients enter the blood
stream. The sugars then enter the cell and move into the mitochondria.
Recall: the mitochondria are the power house of the cell. Energy is made
in the mitochondria.
Cell respiration is the breaking down of glucose in the mitochondria to
make energy in the form of ATP. ATP is adenosine triphosphate. It is a
little molecule that runs around inside your cell to bring energy to the parts
of the cell that need energy.
Respiration:
Cell + glucose = energy (ATP)
Energy is stored in chemical bonds throughout your body. So when you
digest your food and break down the chemical bonds, energy is released.
You may have noticed that you get hot after you eat food. This heat is the
energy that is released in the bond breaking of digesting foods. This energy
is then captured by making new chemical bonds. You make new bonds
when you make up new tissues – muscle, fat, etc.
 break bonds = releases energy
 make bonds = stores the energy
There are two kinds of respiration. They are:
A. Aerobic respiration - uses oxygen and makes lots of ATP.
B. Anaerobic respiration - does not use oxygen and makes small amounts
of ATP.
Aerobic Respiration:
 This occurs in two stages.
 Glucose = C6H12O6
Stage 1: GLYCOLYSIS
* glyco = glucose; lysis = breaking down.
* glycolysis occurs in the cell cytoplasm.
* one glucose molecule (C6H12O6) is broken in half to make two pyruvate
molecules (C3H6O3).
* when bonds are broken, energy is released and stored in the molecule
ATP.
* Equation:
6 Carbon molecule = 3 Carbon +3 Carbon + 2ATP
OR
Glucose = pyruvate + pyruvate + 2ATP
* pyruvate now enters the mitochondria.
Stage 2: OXIDATIVE RESPIRATION:
* called oxidative since oxygen used.
* occurs in the mitochondria.
* pyruvate is broken down into carbon dioxide and water.
* when pyruvate bonds are broken, energy is released and stored in the
ATP molecule.
* two pyruvate broken down = 34 ATP made.
*Equation:
3 Carbon molecule = 3 Carbon dioxide + 3 water + 17 ATP
OR
1 Pyruvate = 3 CO2 + 3 H2O + 17 ATP
Overall reaction for aerobic respiration is:
1 glucose + 6 oxygen = 6 carbon dioxide + 6 water + 36 ATP
Interesting fact:
Cyanide blocks the reactions of oxidative respiration. This disruption
severely reduces the amount of ATP that is made in an animal’s body.
This results in coma and death. That is why cyanide is considered a
poison.