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Bacteria

Group members Rafia Ishmam Rezwana
by

Rafia Anowar

on 24 September 2012

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Transcript of Bacteria

Rafia Ishmam Rezwana Bacteria Bacteria are a large domain of microorganisms. Normally, bacteria are extremely small in length and they have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are found able in most habitats on Earth. Bacteria Antonie Van Leeuwenhoek was the first Person who invented the microscope and discovered the microbial world. Leeuwenhoek was from Delft, Holland. He used to grind lenses to make microscopes. His microscopes could magnify objects about 200-300 times. He was the first person to discover microscope History of bacteriology Bacteria AntonieVanLeewenhoek The ancestors of modern bacteria were single-celled microorganisms and these were the first forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, all of these organisms were microscopic and bacteria. Morphology Origin and early evolution Bacteria shows a wide variety of shapes and sizes, called morphologies. Most of the bacteria are so small that it is impossible to see them without a microscope. Among the smallest bacteria are members of the genus Mycoplasma, which measure only 0.3 micrometres, as small as the largest viruses. Some bacteria may be even smaller, which are called ultramicrobacteria but they are not well-studied yet. Cellular structure Intracellular structure The bacterial cell is surrounded by a lipid membrane, or cell membrane, which encloses the contents of the cell and acts as a shield to hold nutrients, proteins and other essential components of the cytoplasm within the cell. Bacteria do not normally have membrane-bound organelles in their cytoplasm and so contain few large intracellular structures. In most bacteria, a cell wall is present on the outside of the cytoplasmic membrane. Bacterial cell walls are different from the cell walls of plants and fungi. The cell wall is essential to the survival of many bacteria, and the antibiotic penicillin is able to kill bacteria by inhibiting a step in the synthesis of peptidoglycan. Extracellular structure Certain genera of Gram-positive bacteria, such as Bacillus, Clostridium, Sporohalobacter, Anaerobacter and Heliobacterium, can form highly resistant, dormant structures called endospores. In almost all cases, one endospore is formed and this is not a reproductive process, although Anaerobacter can make up to seven endospores in a single cell. Endospores have a central core of cytoplasm containing DNA surrounded by a cortex layer and protected by an impermeable and rigid coat. Endospore Metabolism is a chemical reaction that takes place in the cells of every living thing to maintain life. This allows the different organisms to grow and reproduce, and to respond to their environment. It also helps organism to digest and transport substances between different cells, this reaction is called intermediary metabolism or intermediate metabolism. Metabolism Unlike multicellular organisms, bacteria tends to grow bigger in size, which are tightly linked in unicellular organisms. Bacteria grow up to a fixed size and then after that they reproduce through binary fission. Bacteria can grow rapidly and their population can double as quickly at about 9.8 minutes. Growth and reproduction Genetics Genetics is the science of genes in living organisms. Genetics deal with the function of genes and the structure of molecules, gene behaviour, pattern of inheritance from parents and gene disribution and variation. Human genetics Bacteriophages are viruses that infect bacteria. There are many types of bacteriophages. Some simply infect the bacteria, while the others insert the bacteria chromosome. Bacteriophages Secretion Behavior Bacteria secrete chemical in their environment in order to change it favourably. The chemicals that they secrete are proteins. Few bacterias have chemicals system that produce light. That is called the Bioluminescence and it occurs in bacterias that live in association with fishes, often to attract them. Bioluminescence Bacterias usually function as multicellular aggregates called biofilms. they exchange different types of molecular signals for inter-cell communication and engage in coordinated multicellular behaviour. Multicellularity Bacterias are able to move with the help of different nechanism. Flagella are used for swimming, bacterial gliding help them move across different surfaces. the changes of buoyancy enable the bacterias to move vertically. Movement Classification describes the diverse species of bacterias by naming and grouping species according to similarities.
Identification of bacteria in the laboratory is particularly relevant in medicine, where the correct treatment is determined by the bacterial species causing an infection. Consequently, the need to identify human pathogens was a major impetus for the development of techniques to identify bacteria. Classification and identification Interactions with other organisms Predators The type of bacteria that kill and then consume other microorganisms are called predator bacteria. An example is Myxococcus Xanthus, they form swamps of cells, that kill and digest any microorganism they encounter. Bacterias can interact with other organisms. Their symbolic association can be divided into parasitism, mutualism and commensalism. due to their small size, basterias can grow on plants and animals exactly the way they will grow on normal surfaces. Certain bacteria form close spatial associations that are essential for their survival. One such mutualistic association, called interspecies hydrogen transfer, occurs between clusters of anaerobic bacteria that consume organic acids such as butyric acid or propionic acid and produce hydrogen, and methanogenic Mutualism If bacteria form a parasitic association with other organisms, they are classed as pathogens. Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, foodborne illness, leprosy and tuberculosis. Pathogens Bacteris often, lactic acid bacteria have been used for thoudands years in the preparation of fermentes food, such as cheese, vinegar, wine and yogurt. Significance in technology
and industry http://en.wikipedia.org/wiki/Metabolism
http://en.wikipedia.org/wiki/Bacteria#Classification_and_identification
http://en.wikipedia.org/wiki/Genetics
http://en.wikipedia.org/wiki/Bacteria References
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