Principles of Biology By Frank H. Osborne, Ph. D. Cellular Respiration

Cellular respiration is used to obtain energy. The energy is stored in molecular form (ATP). The by-products of respiration are carbon dioxide and water. The process of respiration is carried out by all living cells, all the time. Even a plant cell in the light will do photosynthesis in the chloroplasts and respiration in the mitochondria simultaneously.

Cellular Respiration Cellular respiration has two phases. Anaerobic phase - does not require oxygen –Fermentation is a partial breakdown of glucose that provides a little quick energy (2 ATP) anaerobically. Aerobic phase –Aerobic respiration is complete oxidation of the glucose molecule. It results in 36 ATP. –Aerobic respiration is more efficient than fermentation.

Cellular Respiration Cellular respiration has two phases: anaerobic respiration aerobic respiration Anaerobic bacteria have only the anaerobic phase. They can obtain energy without oxygen. All other cells have both phases. They use oxygen in the aerobic phase. The CO 2 released from respiration is used by plants for photosynthesis.

Cellular Respiration Anaerobic respiration is carried out using the Embden-Meyerhof pathway, commonly known as glycolysis. Anaerobic respiration is found in all cells, even those that use oxygen. Anaerobic respiration is the only type of respiration found in anaerobic bacteria. These bacteria do not require oxygen for living. Anaerobic bacteria use fermentation for energy.

Cellular Respiration Aerobic respiration involves the oxidation of glucose using oxygen. After glycolysis the Krebs cycle is used. Molecular oxygen is used as the terminal electron acceptor for the respiratory chain.

Cellular Respiration In humans, muscle cells cannot perform oxidative phosphorylation fast enough during vigorous exercise. During vigorous exercise the muscles do fermentation. As a result you get tired and feel a burning sensation caused by lactic acid. So you rest, and the body removes the lactic acid from the muscles.

Cellular Respiration Sugars and carbohydrates are sources of energy for the body. They can also be converted to fats. When there is an excess of carbohydrates in the diet, the body saves them up in the form of fats which are stored in fat cells. This leads to an increase in body fat content.

Topics for First Exam Chemistry (15) Cells (13) Tissues (12) Photosynthesis (5) Cellular Respiration (5)

The End Principles of Biology Cellular Respiration