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BI276 lecture 1 .docx

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Hany Anany

BI276 Life on Earth: Microbes Basic Principles of Microbiology: Ch 1 Lecture 1 Microbiology: • Is the study of microorganisms(single-celled microscopic organisms including viruses) 1. Diversity-variety 2. Evolution- is the change in the inherited characteristics of biological populations over successive generations 3. Ecology- is the scientific study of interactions among organisms and their environment, such as the interactions organisms have with each other and with their abiotic(non-living) environment. • What is the science of microbiology all about? 1. Microbiology is about microbial cells and how they work, especially the bacteria, a very large group of very small cells that, collectively, have enormous basic and practical importance. 2. Microbiology is about diversity and evolution of microbial cells, about how different kinds of microorganisms arose and why. • The Science of Microbiology revolves around two interconnected themes 1. Understanding the living world of microscopic organisms  Microbes are excellent models for understanding cellular processes in unicellular and multicellular organisms. • Can grow rapidly in large numbers in small scale lab cultures. 2. Applying our understanding of microbial life processes for the benefit of humankind and planet earth.  Microbes play important roles in medicine, agriculture, and industry  Casual agents of diseases  Digestive process, recycling of major nutrients elements.  Food industry (safety, processing)  Industry(biofuel) • Microorganisms are independent entities(carry out life processes independently) • Properties of Cellular life 1. What essential properties characterize cells?  All cells show some form of metabolism, they take up nutrients from the environment and transform them into new materials and waste products.  During these transformations, energy is conserved in a form that can be drawn upon by the cells to support the synthesis of key structures.  The final result of any cell’s metabolic activities is to form two cells, in microbiology we use the term growth rather than reproduction to refer to the increase in cell number from cell division.  Cells undergo evolution, the process of descent with modification in which genetic variants are selected based on their reproduction fitness, this process is typically slow, but it can occu rapidly in microbial cells when selective pressure is strong. • Example: the selection for antibiotic resistance in pathogenic (disease-causing) bacteria by the indiscriminate use of antibiotics in human and veterinary medicine.  Many cells are capable of Motility, basically self propulsion. This allows cells to move away from danger or unfavorable conditions and to exploit new resources or opportunities.  Some cells undergo differentiation, which may, ex: produce modified cells specialization for growth, dispersal or survival.  Some cells respond to chemical signals in their environment including those produced by other cells of either the same or different species; this is what thus say that cells exhibit communication. • So, the properties of cellular life are: Evolution, Reproduction (Growth), Motility, Differentiation, and Communication. • Properties of all cell 1. Compartmentalization and metabolism: a cell is a compartment that takes up nutrients from the environment, then transforms them, and releases wastes into the environment. The cell is thus an open system. 2. Growth: Chemicals from the environment are turned into new cells under the genetic direction of preexisting cells. 3. Evolution: Cells contain genes and evolve to display new biological properties. Phylogenetic trees show the evolutionary relationships between cells. • Properties of some cells 1. Motility: Some cells are capable of self propulsion. 2. Differentiation: some cells can form new cell structures such as a spore, usually as part of cellular life cycle. 3. Communication: Many cells communicate or interact by means of chemicals that are released or taken up. • Cells coordinate their catalytic and genetic functions to support cell growth.  In the events that lead up to cell division, all constituents in the cell double. This requires that a cell’s catalytic machinery, its enzymes, supply energy and precursors for the biosynthesis of all cell components, and
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