Microbiology

Microbiology Study Guide

©2018 of 132 Photosynthesis Most living organisms on Earth make use of the molecules of water and carbon dioxide in order to perform metabolic functions and synthesize their food. Unicellular algae and photosynthesizing bacteria, such as cyanobacteria and green and purple sulfur bacteria, are the types of microorganisms that are capable of the process of photosynthesis. There are two major steps in the process of photosynthesis. In the first one, the energy from electrons is trapped when they pass from the coenzymes and other molecules and form energy rich ATP and NADPH molecules. In the second step, the molecules of carbon dioxide are trapped in the carbohydrates using the ATP and NAPDH molecules. This is when organic substances, like glucose, are formed. In the eukaryotic organisms, the process of photosynthesis takes place in the thylakoid membranes, which resemble the mitochondria’s cristae. With the help of the pigment molecules, sunlight is stored in the thylakoid and organized into photosystems. These photosystems include the molecules of pigment, proton pumps, and the coenzymes and molecules of electron transport systems. In contrast, in the prokaryotic microorganisms, the molecules of chlorophyll get dissolved in the cytoplasm of the cell and are termed as bacteriochlorophylls. Two kinds of reactions take place in the process of photosynthesis. The first one is the energy fixing reaction, or light reaction, while the second is a carbon-fixing reaction, also known as dark reaction or Calvin cycle. Regulation Regulation is the control of microbial growth. Some ways to control the growth of microbes are sanitization, sterilization, disinfection, antisepsis, and de-germing. In the event of sterilization, all microbial cells and spores are destructed. Disinfection and antiseptics cause the destruction of the pathogens of microbes but remain ineffective on the bacterial spores. Disinfectants deal with the elimination of microbes from non-living objects, while antiseptics remove the microbes from a living surface. Sanitization does not necessarily kill the microbes but aims to reduce them to a certain acceptable count, as prescribed by public health guidelines. When the microorganisms are removed physically using detergents or soaps, the process is known as de-germing. Germicides are the chemical agents that destruct microorganisms. The species of bacteria are killed using bactericide, while fungicides are used to destroy fungi species. The chemical agent used to kill viruses is known as viricide. The chemical agents that do not kill all the organisms but prevent growth are termed as bacteriostatic. Factors that are vital in the use of germicides are temperature, the nature of the microorganism, and environmental factors. Achieve Page 30

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