MCB2004 Exam 1 Review Guide 15 of human cancer cases are caused by viruses Unaided eye resolution is 0 4mm Microbes organisms that are too small to be seen with the unaided eye 6 major groups of microbes studied by microbiologists 1 Bacteria a Prokaryotes single cell b Peptidoglycan cell wall c Binary fission asexual cell division d For energy use organic chemicals inorganic chemicals or photosynthesis 2 Archaea Lack peptidoglycan a Prokaryotes b c Commonly live in extreme environments d 3 Fungi a Eukaryotes cell contains a nucleus b Chitin cell walls c Use organic chemicals for energy d Yeasts are unicellular molds and mushrooms are multicellular 4 Protozoa 5 Algae a Eukaryotes b Absorb or ingest organic chemicals c My be motile via pseudopods cilia or flagella a Eukaryotes b Cellulose cell walls c Use photosynthesis for energy d Produce molecular oxygen and organic compounds 6 Viruses a Acellular b DNA or RNA genome Includes methanogens extreme halophiles high concentration of salt and extreme thermophiles i Genome surrounded by protein coat called a capsid ii Coat may be enclosed in a lipid envelope c Replicated only when they are living in a host cell What is a microbe Microbes are living creatures except viruses Have proteins nucleic acids lipids and sugars same as us chemically Metabolize grow reproduce and respond to environment Microbial genomes many are sequenced Genome organism s total genetic content First draft of human genome was published in 2000 Microbes have the greatest diversity of genomes Studying them is important for studying evolution Uses for microorganisms 1 Produce fermented foods such as bread and cheese 2 Produce industrial chemicals such as ethanol and acetone 3 Produce medicine vaccines and products used in manufacturing e g cellulase 4 Widely used as tools in biomedical research 5 Decompose organic waste sewage treatment bioremediation 6 Producers in the ecosystem by photosynthesis 7 Some are pathogenic disease causing To Decrease Growth of Microbes To Increase Growth of Microbes Prevent food spoilage Prevent disease occurrence public health personal hygiene anti microbial drugs vaccine Prevent contamination in medicine and in microbiology laboratories Make fermented food Make medicine industrial products Recycle waste Biological control BT as pesticide Less than 1 of microorganisms are culturable and studied Eukarya protists fungi plants and animals Robert Hooke 1665 reported living things are composed of little boxes cells Cell theory all living things are composed of cells and come from preexisting cells Aton von Leeuwenhoek 1673 1723 described live microorganisms Where do microbes come from 1 Spontaneous generation all living organisms arise from nonliving matter 2 Biogenesis living organisms arise from preexisting life Francesco Redi s experiment on maggots sealed jars no maggots open jars maggots appeared John Needham put boiled nutrient broth into covered flasks When the nutrient broth was heated and placed in a sealed flask it led to microbial growth Lazzaro Spallanzani boiled nutrient solutions in flasks The flask was heated and sealed however led to no microbial growth Pasteur Poured beef broth into a long necked flask microorganisms were present in the broth heated the neck of the flask and bent it into an s shape boiled the broth for several minutes microorganisms not present in broth after boiling microorganisms did not appear in the cooled solution even after long periods bend prevented microbes from entering flask Pasteur showed that microbes are responsible for fermentation the conversion of sugar to alcohol Bacteria can also spoil food by using alcohol and turning it into acetic acid Pasteur spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine Pasteurization application of high heat for a short amount of time The Germ Theory of Disease 1860s Applying Pasteur s work showing microbes are in the air can spoil food and cause animal diseases Joseph Lister used a chemical disinfectant to prevent surgical wound infections 1876 Robert Koch proved that a bacterium causes anthrax and provided the experimental steps Koch s postulates that prove a specific microbe causes a specific disease Koch s Postulates 1 Detect agents in the host s with the disease 2 3 4 Re isolate the agent Isolate pure culture agent Induce disease in new host Golden Age of Microbiology 1857 1914 beginning with Pasteur s work 1 1857 Pasteur Fermentation 2 1861 Pasteur disproved spontaneous generation 3 1864 Pasteur Pasteurization 4 1867 Lister Aseptic surgery 5 1876 Koch Germ theory of disease 6 1881 Koch Pure cultures 7 1887 Petri Petri dish Chemotherapy treatment with chemicals Can be synthetic drugs or antibiotics chemicals produced by bacteria and fungi that inhibitor kill other microbes The first synthetic drugs Quinine from tree bark malaria Paul Ehrlich magic bullet that could kill pathogen without harming host In 1910 developed a synthetic drug salvarsan to treat syphilis Alexander Fleming discovered the first antibiotic He discovered penicilium could form the antibiotic penicillin to kill staphylococcus aureus 1940s Penicillin tested clinically and mass produced Fleming Chain Florey Recombinant DNA DNA made from two different sources In the 1960s Paul Berg inserted animal DNA into bacterial DNA and the bacteria produced an animal protein Biotechnology use of microbes to produce foods and chemicals Through genetic engineering bacteria and fungi can produce a variety of proteins including vaccines and enzymes Gene therapy missing or defective genes can be replaced Botox is a neurotoxin made from the bacteria Clostridium botulinum Botulinum toxin is one of the most poisonous natural substances and the most toxic protein Botox decreases muscle activity Bacteria recycle carbon nutrients sulfur and phosphorus that can be used by animals Bacteria can also degrade organic matter in sewage and can detoxify pollutants such as oil and mercury Microbes that are pathogenic to insects are alternatives to chemical pesticides in preventing insect damage to crops and disease transmission i e Bacillus thuringiensis Microbiota microflora microbiome microbes normally present in and on the human body Normal microbiota prevent growth of pathogens and produce growth factors such as folic acid and vitamin K Emerging infectious disease EID new diseases and diseases increasing in incidence 1800 Mortality 50 due to infectious diseases now 5
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