Cellular Respiration

Cellular Respiration occurs in Heterotrophs or Consumers.

Heterotrophs are organisms which are unable to produce their own food and obtain energy through the breaking of chemical bonds of the food.

Cellular respiration is the breaking down of glucose with the help of oxygen to make energy in the form of ATP and is the release of water and carbon dioxide.

Cellular Respiration

Chemical Formula C

6H

12O

6 + 6 O

2→ 6 H

2O + 6 CO

2 + 38 ATP

Cellular respiration takes place in the cytoplasm and the mitochondria of the cell

Cellular RespirationStage I – Glycolysis / Anaerobic

The first stage is called glycolysis. Glycolysis means breaking apart of glucose. Glucose in the cytoplasm is acted upon by two ATP

which breaks the glucose molecule into two parts.

C 6 H

12 O

6 > C

3H

6 O

3

> C3 H

6 O

3

Cellular RespirationStage I – Glycolysis / Anaerobic

There is enough energy for one hydrogen to be removed from each part and attach to NAD to make NAD + H C

3 H

6 O

3 - H = C

3 H

5 O

3

NAD + H C3 H

6 O

3 - H = C

3 H

5 O

3

There is also enough energy from each part for 2 phosphates to join with two ADP.

This makes a total of 4 ATP.

Since two ATP were used to start the process and four are made, there is a net gain of two ATP.

Cellular RespirationStage II - Aerobic

The second part of cellular respiration starts. This stage takes place in the mitochondria. The bean shaped mitochondria is filled with

folds of membranes called cristae and between the membranes are a matrix.

Cellular RespirationStage II – Aerobic

Once in the mitochondria the pyruvic acid is acted on by coenzyme A which causes a hydrogen to be removed and attach to NAD as well as a CO

2.

The product (C2 H

4 O) is call Acetic Acid.

Acetic Acid enters a cycle called the Krebs cycle.

Cellular RespirationKrebs Cycle

Acetic Acid joins with 4 carbons. This is now

C6 H

4 O.

3 O2 molecules, which are in the cell, oxidize

the compound. Oxidation is a process which causes chemical reactions to take place. During oxidation, the 4 hydrogen are removed and each joins a NAD/ FAD. Two Carbon molecules bond with 4 oxygen and form 2 CO

2 .

Cellular RespirationKrebs Cycle

This leaves four carbon and 3 oxygen molecules. The oxygen will eventually bond with the trapped hydrogen and form water. The four carbons will join acetic acid and keep the cycle going.

For one glucose molecule the cycle must occur two times.

Cellular RespirationElectron Transport Chain

The trapped hydrogen electrons must first lose energy before they can bond with oxygen.

The electrons pass along a pathway called the electron transport chain. Each step along this pathway energy is released and the energy is used to bond a phosphate with ADP to make ATP.

Finally the 6 oxygen molecules bond with the 12 hydrogen and make 6 water molecules.

Cellular RespirationATP formation

In Glycolysis 4 ATP are formed For each hydrogen held by NAD, 3 ATP are

formed. For the two hydrogen held by FAD, 2 ATP are

made. 4 + 30 + 4 = 38 ATP