by Tmari

Created on: April 25, 2010

The energy needed for survival is furnished to plants and animals through various chemical processes; the sunlight provides much of the energy these living organisms rely on for nourishment. Cells are also dependent upon energy; cells need energy to function properly. Plants need energy to grow and to reproduce; energy is one of the main resources of all living organisms. Cellular respiration ensures that living organisms receive enough energy to sustain life. Pruitt & Underwood (2006) explains, “Cellular respiration is the name given to the metabolic pathways in which cells harvest the energy from the metabolism of food molecules.” (p. 289). Food provides the nutrients living organisms need to stay healthy and for maturity elements.

How Does Cellular Respiration Yield ATP?

Cellular respiration yields adenosine triphosphate (ATP) through various metabolic stages; as each phase occurs, molecules of ATP are formed to provide a much needed source of energy. Cellular respiration occurs in three stages; glycolysis, the krebs cycle, and the electron transport system. Pruitt & Underwood (2006) reports, “Glucose breakdown occurs within cells as a continuous sequence of sequence of 25 steps.” “…when we look at this continuous process carefully, it is apparent that these steps can be grouped into three separate stages,” “We call these stages glycolysis, the krebs cycle, and the electron transport system, also known as the electron transport train.” (p. 289).

Glycolysis takes place in the cytoplasm; this is the first stage of cellular respiration it goes through ten steps to produce ATP for living organisms. Pruitt & Underwood (2006) informs, “In glycolysis, (which means “sugar splitting”), the six-carbon sugar, glucose, is split in half to make two three-carbon compounds, and hydrogens are stripped from carbons.” “The energy of the broken bonds is captured, and there is a net yield of ATP. (p. 289). Four molecules of ATP are formed in glycolysis, but only two molecules of ATP are present once the glycolysis process is completed. The krebs cycle is essential to the production of more ATP. Pruitt & Underwood (2006) repots, “For the Krebs cycle…First, chemical energy entered the pathway in the form of acetyl CoA, and second, chemical energy left the Krebs cycle in the form of ATP, NADH, and FADH2.” (p. 293). Thus, the krebs cycle has set the stage for

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