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Bacteria and Viruses Chapter 19 I. Bacteria (Prokaryotes) A. Characteristics of prokaryotes (bacteria cells) 1. single celled 2. no nucleus 3. smallest and most common organisms 4. microscopic B. How to identify prokaryotes: 1. Shape a. bacillus – rod shaped b. cocci – spherical shaped c. spirilla – spiral shaped 2. Movement (motility) a. Structure that allows movement is called a flagella, a whip-like tail b. Not all bacteria can move 3. How they get energy (Autotroph, Heterotroph or both) 4. Type of cell wall C. Two kingdoms of bacteria (prokaryotes): 1. Kingdom Eubacteria a. most common type of bacteria b. live almost everywhere (in side or outside the body, fresh water, salt water, land, etc) c. very diverse d. have special layer in cell wall called peptidoglycan e. Sketch: (see Fig. 19-2 p. 472) Structure Function a: cell wall protection b: cell membrane protection c: ribosomes make proteins d: pilli stick to surface e: DNA genetic info f: flagellum movement 2. Kingdom Archaebacteria a. live in harsh environments (ex: hot springs, oxygen-free environments, or extremely salty areas (Utah’s Salt Lake) b. genes are more similar to eukaryotes than eubacteria D. Bacteria reproduction: a. binary fission (asexual) b. conjugation (sexual) c. form spores (form a protective layer that allows a bacteria cell to survive until conditions are more favorable E. Importance of bacteria - vital to maintaining the living world! a. bacteria are decomposers (break down sewage, dead/decaying organisms b. bacteria in soil go through nitrogen fixation – the process of changing nitrogen into NH3, a useable form of nitrogen for plants c. human intestines have large numbers of bacteria and produce vitamins that our body cannot make by itself (symbiotic relationship) II. Viruses A. Characteristics a. non-living (do not grow, use energy, or respond to environnment) b. contain DNA or RNA surrounded by a protein coat (capsid) c. cannot reproduce without a host cell (A host cell is a cell that a virus invades) d. Sketch (see Fig. 19-9 p. 479) Structure A. B. C. D. Capsid (protein coat) Tail Sheath DNA Tail Fiber B. Virus infection a. Lysogenic cycle step 1: virus enters the cell step 2: virus DNA replicates with each bacterial generation step 3: virus enters lytic cycle b. Lytic cycle step 1: virus enters cell step 2: cells makes copies of virus causing cell to burst (Lyse) III. Disease A. Bacterial Disease a. Can damage cells and tissues as they are used as food source 1. ex: M. tuberculosis – destroys lung tissue 2. ex: B. anthrasis – (anthrax) can infect humans and animals; spore forming; can be deadly 3. see chart on p. 486 for more examples b. Can produce toxins (poisons) ex: C. diptheriae – releases toxins into bloodstream B. Treatment of bacterial disease a. antibiotics – block growth and reproduction of bacteria b. vaccine – a solution containing dead or weakened pathogens; when injected into body, it prepares body to overcome the pathogen if it enters body later C. Viral disease a. attack and destroy certain cells and tissues in body b. CANNOT be treated with antibiotics c. can infect all kinds of cells (plant, bacteria, human) d. vaccines provide protection if taken BEFORE viral infection (PREVENTION = VACCINATIONS!!) e. Examples: poliovirus – attack nervous system; movement problems smallpox – high fever and disfiguring rash human papillomavirus (HPV) – warts D. Prion disease – infectious proteins ex: “mad cow disease”