Microbiology

Microbiology Study Guide

Cellular respiration process:

Glycolysis Glycolysis takes places in the cytoplasm of cells and consists of a number of steps for the metabolic pathway. It does not make use of oxygen, and thus, is known as an anaerobic process. It provides a major source of energy to most of the anaerobic organisms like yeasts and bacteria. The energy is released in the molecules with the help of ATP during the first and third phase of glycolysis, and thereby two molecules are expanded. In the process, intermediary compounds are formed and are split into three carbon compounds with the help of six carbon glucose molecules. Thereafter, pyruvic acid is formed after the molecule undergoes further conversions and transformations. At the later stages, the energy derived from the chemical reaction is used to synthesize four molecules of the ATP cell. Moreover, abundant amount of energy is released that helps to form NADH from NAD, which is used in the electron transport system. In the process, a total of two NADH molecules are formed. This phase is considered inefficient since not all energy is processed and remains in two of the molecules of the pyruvic acid. The Krebs Cycle The Krebs Cycle is also known as citric acid cycle. The two molecules of the pyruvic acid are taken in this step so that the high energy molecules of NADH and FADH are formed. Further, ATP and carbon dioxide are released in this step. Fermentation Irrespective of the absence of oxygen, it is possible to release energy from glucose through fermentation. Since oxygen is not used, the process of fermentation is anaerobic. Fermentation usually takes place in yeast as well as bacteria cells. In the case of yeast cells, the metabolic activity takes place with the help of cellular respiration. With the help of glycolysis, glucose is converted into pyruvic acid, which is further transformed in acetaldehyde and then to ethyl alcohol. The final outcome in the case of yeast cells is the formation of two molecules of ATP. Since the yeast cells are able to convert pyruvic acid to ethyl alcohol, they have the fermentation capability. Yeasts are used in the fermentation of alcohol and bread and related products.

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