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Download Viruses - a microscopic particle that invades and often destroys a cell
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Viruses - a microscopic particle that invades and often destroys a cell. - Not considered alive, since they are not made of cells, do not take in food, or get rid of wastes. - They can reproduce, but only with the help of a host, so alive or not? A virus has two basic parts A. Protein coat- protects virus, some viruses have survived for years after drying and freezing B. Hereditary material - either RNA or DNA that produce new viruses How Viruses Reproduce (Lytic Cycle) They inject its RNA or DNA into a host cell and causes the host cell to produce more viruses until the host cell bursts open releasing hundreds of new viruses. Bacteria - Smallest and simplest living things - first form of life on Earth -no nucleus, so it is a prokaryote - reproduce by binary fission (simple cell division) - can survive for millions of years by forming a thick protective coat called an endospore. Bacteria have 3 shapes: 1. Bacilli or rod shaped 2. Cocci or spherical 3. Spirilla or spiral shaped Kingdom Eubacteria - most bacteria - some are consumers (decomposers, parasites) - some are producers (photosynthetic or chemosynthetic) Kingdom Archaebacteria - genetically different from the other bacteria, may have no cell wall - live in extreme environments (salty, hot) - some live in swamps, marshes, excrete methane Bacteria’s Role Good for the Environment 1. nitrogen fixing bacteria change nitrogen in the air into a form plants can use 2. bacteria return nutrients from dead things back into the environment 3. some bacteria can break down harmful pollutants into harmless chemicals (bioremediation) Helpful Bacteria 1. genetically engineered bacteria are used to produce medicines like antibiotics and insulin, insecticides, foods, etc. 2. used to make foods like cheese, yogurt, sour cream, etc. 3. in your intestine, they help digest food and help you absorb vitamins Harmful Bacteria - pathogenic bacteria cause diseases in people, plants, protists, and fungi
