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Transcript
Introduction to BIOL 2421 Course Syllabus Lecture Meeting Times: TR 12:15 – 2:55 pm Textbook: Microbiology, An Introduction, 6th edition (with CD-ROM) by Tortura, Funke, and Case Lab Manual: Microbiological Applications (Short Version) by Benson Grading Procedures/Exams No Makeup Exams will be given Attendance Introduction to Microbiology Microorganisms are ubiquitous They are present everywhere in the environment, as well as in and on our bodies. Why study them? Microorganisms can be both beneficial and harmful. Beneficial examples: Food preservation, flavor, biogeochemical recycling, vitamins (enterics) Harmful examples: disease, food blights, spoilage History of Microbiology FIRST MICROSCOPIC OBSERVATIONS AND CELL THEORY: 1665 - Robert Hooke (England) described "little boxes" or "cells beginning of the cell theory of life, i.e. all living things are composed of cells 1673 - Antoni van Leeuwenhoek (Holland) 1st to observe live microorganisms, "animalcules" observed what are now recognized to be bacteria and protozoa Spontaneous generation debate: common belief that organisms arose by spontaneous generation certain substances giving rise to specific types of organisms (flies from manure, toads from mud, etc.) 1668 (before microscopic observations), Francesco Redi (Italy) - showed maggots not from decaying meat when no maggots grew on meat which was sealed in jars (Opponents - air necessary for life, some still believed that simple organisms would arise spontaneously) Pro: 1745 - John Needham (England) microbes still grew after heated nutrient fluids were poured into covered containers Con: 1765 - Lazzaro Spallanzani (Italy) proposed that microorganisms came from air in Needham's samples, found none in broth after heating in sealed containers opponents said "vital force" destroyed by heating and couldn't enter sealed flask 1858 - Rudolf Virchow (Germany) biogenesis - all cells arise only from preexisting cells 1861 - Louis Pasteur (France) heated broth in open flasks with s-shaped necks -- final blow to spontaneous generation theory. The discoveries by Pasteur and others lead to the development of aseptic technique the most important techniques that all microbiologists use methods for preventing contamination by unwanted microorganisms Pasteur also introduced Pasteurization heating which kills pathogens (disease-causing) organisms, but does not damage the food (milk). 70oC 15 seconds. Is not sterilization. Used primarily on milk, cream, beer, wine. Germ theory and Koch's Postulates: Pasteur's findings about fermentation by microorganisms led to the idea that they might be involved in disease. This is the germ theory of disease. Ignaz Semmelweis (1840's, Hungary) showed that simply washing hands by doctors between obstetrical patients reduced the incident of childbirth fever Joseph Lister (1860, England) applied germ theory to medical procedures, using phenol (an organic acid) to treat wounds (found less incident of infections, many other doctors applied this technique). Robert Koch (1876, German physician) First direct proof of bacteria causing disease Linked bacterium, Bacillus anthracis, to anthrax. Developed steps to experimentally determine if a microorganism is involved in a disease 1. The same pathogen must be present in every case of the disease 2. The pathogen must be isolated from the diseased host and grown in pure culture 3. The pathogen from the pure culture must vause the disease when it is inoculated into a healthy, susceptible animal 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism. Waging war - advances in combating microbial diseases: vaccines - 1796 (before Koch) Edward Jenner (British physician) Developed first vaccine – Jenner was told by a young milkmaid that she couldn’t get smallpox because she had already been sick from cowpox (milder disease) He decided to test her tale… collected scrapings from cowpox blisters and inoculated a healthy 8yr old volunteer with these scrapings. Scratched arm with contaminated needle. WHY doesn’t this bright milkmaid get more credit for her observations? Origins of immunology - studied since Jenner, use of body's own defense mechanisms antimicrobials/antibiotics "magic bullet" idea, Paul Ehrlich (Germany), early 1900's. Speculated about a ‘magic bullet’ medicine for particular diseases that would ‘hunt/kill’ disease organisms without harming the patient. Tested hundreds of chemical agents before finding SALVARSAN (arsenic derivative) which was effective against syphilis Alexander Fleming (Scotland), 1928, accidently discovered fungus inhibiting bacteria – tossed out some cultures that were contaminated by mold… later on taking a second look noticed a clear around the mold where no bacteria were growing. Mold inhibited bacterial growth. Mold was Penicillium notatum Fleming later named the mold’s inhibiting factor penicillin Virology 1892, Dmitri Iwanowski speculated about tobacco mosaic virus. Reported that the factor causing the disease was so small that it was not filtered out by filters small enough to stop all known bacteria. Did NOT understand the organism as a virus as we now understand it 1935, Wendel Stanley crystallized TMV, showed it was different than cellular life. 1940's - electron microscope allowed direct visualization of virus particles. Naming and Classification Binomial nomenclature System of naming 1735, Carolus Lennaeus, based on latin consists of: Genus species Classification 5 Kingdoms: Whittaker Monera, Protista, Fungi, Plantae, Animalia 3 Domains: 1978, Carl Woese Eubacteria, Archaea, Eukarya Main groups of microorganisms: Prokaryotes – NO NUCLEUS Bacteria and Archaea Eukaryotes – Genetic material enclosed in membrane – nucleus ,Fungi, Protozoa, Algae, Multicellular animal parasites Microorganisms Bacteria – single celled, no nucleus, cell walls contain peptidoglycan (sugar/amino acid combination) – structural molecule. Reproduce by binary fission. Derive nutrients from organic materials, which can come from living or dead organisms. Some make food via photosynthesis; some can use inorganic compounds as a food source. Archae- similar to bacterial (no nucleus) cell walls lack peptidoglycan. Found in extreme environments (Great Salt Lake, Dead Sea, hot springs, thermal vents) Three major groups of archae methanogens – produce methane as a waste product extreme halophiles – thrive in high salt environments extreme thermophiles – thrive in hot waters Fungi – are eukaryoutes. HAVE NUCLEI. Unicellular or multicellular. Cell wall of chitin. Reproduce sexually or asexually (eg. budding) yeast is a unicellular fungi larger than bacteria. Other fungi include molds which form visible mycelia. Obtain nutrients from organic material in their environment. Protozoa – unicellular, eukaryotic microbes like Amoeba, Paramecium etc. Reproduce sexually or asexually, many shapes, some are parasites, derive nutrients from environment. Many are mobile moving by pseudopods (flowing), flagella or cilia. Algae – photosynthetic eukaryotes, many have cell wall made of cellulose (like plants) present in soil, water (fresh/salt). Unicellular or multicelluar/colonial. Viruses – vastly different from other life forms. Contain a core of nucleic acid (RNA or DNA) – surrounded by protein coat. Must use cellular machinery of other organisms to reproduce. All are parasites. Multicellular Animal Parasites – not strictly microorganisms, but are medically important. Includes flatworms and roundworms.