Microbiology

Microbiology Study Guide

The Phosphorus Cycle Compounds of phosphorous are used by living beings in the fusion of proteins, such as nucleotides, phospholipids, and phosphorylate. When crops in the soil break, the ions of phosphorous in the form of calcium phosphate, magnesium phosphate, and iron phosphate enter the soil and water resources. Next, these phosphates enter into organic compounds (like DNA and RNA) with the help of phospholipids. Finally, the phosphorous becomes a part of the food chain when larger organisms consume those organisms rich in phosphate ions. The Sulfur Cycle Although the contribution of sulfur is very small in the weight of a living cell (that is about one percent), it is highly useful in the creation and formation of many enzymes and amino acids. Some of the acids formed with the help of sulfur are cystine, methionine, and glutathione. In the sulfur cycle, the metabolism of the photosynthetic bacteria takes place with hydrogen sulfide. Next, the element sulfur is released after the hydrogen sulfide is oxidized, which is accumulated in the elements of soil. The sulfur bacteria of soil, belonging to the species of Thiobacillus, Beggiatoa , and Thiothrix, metabolize with this hydrogen sulfide to form sulfate ions, which are formed in amino acids and consumed by plants in soil. The Carbon Cycle The majority of the organic matter in soil is formed from the composition of dead leaves, parts of decaying roots of trees, and dead tissues of plants and animals. The carbon in the proteins, carbohydrates, and fats in these dead components are recycled with the help of the bacteria and fungi in the soil through metabolism. Recycling of carbon is an important feature of life, as these provide essential nutrients. The extracellular microbes digest this organic matter and convert them into soluble products. The complex products are then broken down into simpler molecules, like carbon dioxide, acetic acids, and propionic acids by the metabolic activities of fungi and bacteria in the soil. These simpler products act as essential nutrition for the growth of plants, which penetrate to the roots of plants and trees. However, the matter that is not digested by these organisms becomes a part of the humus in the soil. The Oxygen Cycle Oxygen is a vital element that facilitates chemical reactions in the cellular respiration of all organisms. The major source of oxygen lies in the atmosphere. In the oxygen cycle, the oxygen is used and returned back to the atmosphere so that the photosynthetic activity of plants and cynobacteria becomes possible. In the process of photosynthesis, oxygen is released by these organisms in the atmosphere from the water. This oxygen is then used by the heterotrophic organisms so as to undertake the metabolism activity.

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