Georgetown ISD



Chapter 1 A Brief History of MicrobiologyI. Microbiology IntroductionA. General information1. 1/3 of world’s population live on less than $1.00/day, are malnourished, and not immunized2. approximately 12 million people worldwide die each yr. from infections3. bacteria evolved over 3.5 billion yrs. ago4. microbes make up by weight 2/3’s of Earth’s living material5. through photosynthesis microbes produce about 50% of the O2 we use6. normal flora – microorganisms that begin to colonize body at birth – live in/on body – healthy state7. opportunistic pathogens – organism doesn’t usually cause disease; due to circumstances disease can occur – yeast infections, thrush, staphB. Study of microorganisms1. mycology (study of fungi)2. Parasitology (study of parasites)3. virology (study of viruses – over 3600 known viruses)4. bacteriology (study of bacteria – over 10 million known species)5. protozoology (study of protozoa – like the amoeba)6. phycology (study of algae)7. helminthes (parasitic worms)II. The Early Years of MicrobiologyA. What does life really look like:1. Antoni van Leeuwenhoek (Dutch) 1632-1723a. lens grinder and tailorb. made/used simple microscopesc. looked at water and saw tiny animals, fungi, algae, and protozoa: animalcules2. all are now called microbes/microorganismsB. How can microbes be classified1. Carolus Linnaeus – 1707-1778a. taxonomic system b. groups similar organisms together and gives them namesc. still used today2. Leeuwenhoek’s microorganisms grouped into 6 categoriesa. bacteriab. archaeac. fungid. protozoae. algaef. small multicellular animalsC. Bacteria and archaea1. prokaryote2. unicellular3. much smaller than eukaryotes4. found where sufficient moisture is found5. reproduce asexually6. 2 kindsa. bacteria-cell walls composed of peptidoglycan-detritivores-can cause disease-most are beneficialb. archaea -cell walls composed of polymers other than peptidoglycan-found in extreme environments-do not cause diseaseD. Fungi1. eukaryotic2. consumer3. have cell walls4. includes:a. molds-multicellular-grow as long filaments-reproduce sexually and asexually by sporesb. yeast-unicellular-reproduce asexually by budding or sexually by sporesE. Protozoa1. eukaryotic2. unicellular3. found in water, animals4. asexual and sexual reproduction5. most are capable of locomotiona. pseudopodiab. ciliac. flagellaF. Algae1. unicellular or multicellular2. photosynthetic 3. simple reproductive structures4. grouped based on color, storage products, and composition of cell wallG. parasitic worms (helminthes)1. immature stage microscopic2. adult stage often visible with naked eyeH. viruses1. only seen with electron microscope (1932)2. acellular obligate parasitesIII. The Golden Age of Microbiology (late 1800’s-early 1900’s)A. Scientists searched for answers to 4 questions1. Is spontaneous generation of microbial life possible?2. What causes fermentation?3. What causes disease?4. How can we prevent infection and disease?5. Discoveries led to:a. scientific methodb. industrial microbiology (biotechnology)c. biochemistryd. etiology (cause of disease)e. infection controlf. epidemiology (study of occurrence, distribution, and spread of human disease)g. immunologyB. Some thought living things arose from 3 processes1. asexual reproduction2. sexual reproduction3. nonliving matter – spontaneous generation or abiogenesisC. Aristotle – 384-322 B.C.1. proposed spontaneous generation2. lasted 2,000 years3. not challenged until 17th centuryD. Redi’s experiments1. involved jars of raw meat covered and uncovered2. uncovered meat had flies and then maggots; covered meat did not3. result – doubting of Aristotle’s theoryE. Needham’s experiments1. boiled beef gravy and infusions of plant material2. broth placed in flask sealed with cork3. broth turned cloudy with microbes in a few days4. reinforced Atistotle’s theoryF. Spallanzani’s experiments1. repeated Needham’s experiments but melted neck of flask2. broth remained microbe free3. conclusion:a. Needham failed to heat vials enough to kill microbes and/or had not sealed flasks properly\b. microorganisms exist in air and can contaminate experimentsc. Spontaneous generation does not occur4. critics:a. sealed flasks didn’t allow enough air for organisms to surviveb. overheated and killed everythingG. Pasteur’s experiments – finally proved biogenesis - 18591. repeated Spallanzani’s experiment but bent neck of flask2. when “swan-necked” flasks remained upright (18 mos.) no microbial growth3. when flask tilted, dust from bend in neck seeped back into flask and made infusion cloudy withmicrobes within a dayH. Scientific Method1. debate led in part to scientific method:a. observation leads to questionsb. question generates hypothesisc. hypothesis tested through carefully controlled experimentd. results prove or disprove hypothesis-accepted hypothesis leads to theory/law-reject or modify hypothesisI. What causes fermentation?1. spoiled win threatened livelihood of 19th century French vintners2. some believed air caused fermentation3. others said living organisms caused it4. this debate also linked to debate about spontaneous generation4. vintners funded research to prevent spoilage during fermentationa. reached out to Pasteur b. due to Pasteur’s research for vintners, he developed germ theory of fermentation- yeast ferment grape juice into alcohol -bacteria ferment grape juice into acidsc. heat wine – Pasteurization – kills bacteria and reduces their # 5. Buchner’s experimenta. fermentation does not require living cellsb. enzymes promote chemical reactionJ. What causes disease?1. Pasteura. germ theory of disease - 1857-microorganisms cause disease-linked to discovery that bacteria spoiled wineb. led to etiology – study of cause of disease c. known as Father of Microbiology 2. Robert Koch studied causative agents of disease – 1843-1910a. studied anthraxb. examined colonies of microorganismsc. proved bacteria caused anthraxK. Koch’s contributions1. simple staining techniques2. 1st photomicrograph of bacteria3. 1st photomicrograph of bacteria in diseased tissue4. techniques of estimating CFU/mL (colony forming units per milliliter)5. use of steam to sterilize media6. use of petri dishes7. developed solid culture surface (agar)8. techniques to transfer bacteria9. bacteria as distinct speciesL. Koch’s postulates – series of steps one must take to prove cause of any infectious disease1. suspected causative agent must be found in every case of the disease and be absent from healthy host2. agent must be isolated and grown outside host3. when agent is introduced into a healthy, susceptible host, host must get disease4. same agent must be found in diseased experimental hostM. Gram’s Stain – 18441. Danish scientist Hans Christian Gram developed more important staining technique than Koch’s2. involves applications of series of dyes3. some microbes turn purple – Gram positive4. some microbes turn pink – Gram negative5. gram procedure used to separate organisms into 2 groups6. most widely used staining techniqueN. How can we prevent infection and disease?1. Semmelweis and handwashing – 1818-1865a. ob dr. b. wash hands with chlorinated lime waterc. mortality rate dropped from 18.3% to 1.3%2. Joseph Lister’s antiseptic technique - 1827-1912a. sprayed wounds/surgical incisions/dressings with carbolic acidb. death rate dropped by 2/3’s3. Florence Nightingale and nursing a. set standards of hygieneb. opened 1st nursing school4. John Snow - 1854a. during cholera epidemic in London discovered it spread by contaminated waterb. laid groundwork for our public health systems and water treatmentc. led to infection and epidemiology 5. Edward Jenner’s smallpox vaccine -1796a. cowpox material from milkmaid scratched into skin of James Phipps and his sonb. neither got smallpoxc. led to field of immunology6. Paul Ehrlich’s magic bullets – 1854-1915a. salvarsan – cpd. of arsenic to cure syphilis and sleeping sicknessesb. led to field of chemotherapy7. Pasteur - vaccines for anthrax, fowl cholera, rabies, and chicken poxIII. The Modern Age of MicrobiologyA. Beijerinck – 1932 – discovered virusesB. Polio vaccine1. Jonas Salk – 1955 – injection 2. Albert Sabin – 1961 – oral polio vaccineC. What are the basic chemical reactions of life?1. biochemistry – study of metabolisma. began with Pasteur’s and Buchner’s worksb. microbes used as model systems for biochemical reactionsc. practical applications-design of herbicides and pesticides-diagnosis of illness and monitoring responses to treatment-treatment of metabolic diseases-drug designD. How do genes work?1. microbial genetics2. molecular biology3. recombinant DNA technology4. gene therapyE. Microbial genetics1. Avery, MacLeod, and McCarty: genes are contained in molecules of DNA2. Beadle and Tatum: a gene’s activity is related to function of the specific protein coded for by that gene3. Translation of genetic information into protein explained4. rates and mechanisms of genetic mutation investigated5. control of genetic expression by cells describedF. molecular biology1. explanation of cell function at molecular level – genome sequencing2. Linus Pauling proposed gene sequences could:a. provide understanding of evolutionary relationships/processesb. establish taxonomic categoriesc. identify microbes that have never been cultured (some can’t be cultured in lab setting such as bacteria that causes Cat Scratch Disease)3. Woese determined cells belong to bacteria, archaea, or eukaryotesG. Recombinant DNA technology – genetic engineering1. genes in microbes, plants, and animals manipulated for practical applications2. production of human blood-clotting factor by E.coli to aid hemophiliacsH. gene therapy1. inserting a missing gene2. repairing a defective one by inserting desired gene into host cellsI. What roles do microorganisms play in the environment?1. bioremediation uses living bacteria, fungi, and algae to detoxify polluted environments2. recycling of chemicals such as carbon, nitrogen, and sulfurJ. How do we defend against disease?1. serologya. study of blood serum-clear, yellowish, fluid part of blood. Does not contain cells or clotting factor. Does include some proteins, electrolytes, antibodies, antigens, hormones, and any extra substances such as drugs and microorganismsb. blood has chemicals and cells that fight infection2. immunology-the study of body’s defense against specific pathogens3. chemotherapya. Sir Alexander Fleming – 1881-1955- accidentally discovered penicillin - 1928- comes from green mold Penicillium notatumb. Domagk – discovered sulfa drugsK. Future of Microbiology1. New concerns in microbiologya. emerging infectious diseases (diseases recently surfaced in populations):SARS, Ebola, West Nile virus, Hepatitis Cb. re-emerging infectious diseases (diseases that have existed in past but are now showing a resurgence in incidence or a spread in geographic range):Group A Strep, mumps, Staphylococcus aureus, rabies, malaria, TB, cholera, salmonella, Pertussis (whooping cough), Pneumococcus, E. coli, giardiasisc. super microbes – drug resistantd. polymicrobial diseases – 1 disease caused by more than 1 infectious agent:acute necrotizing ulcerative gingivitis, some respiratory diseases, some middle ear infections,Multiple Sclerosis, Pertussis, Hepatitis, gastroenteritis, genital infectionse. bioterrorism2. What prevents certain life forms from being grown in labs?3. Can microorganisms be used in ultraminiature technologies such as computer circuit boards?4. How can understanding of microbial communities help us understand communities of larger?organisms? ................
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