Images gram stain of staphylococcus tport enzyme beta

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Images: Gram stain of Staphylococcus , T.Port; Enzyme Beta- lactamase, J. Swaminathan & MSD staff, European Bioinformatics Institute; Staphylococcus aureus on antibiotic test l t PHIL #2641 From the Virtual Microbiology Classroom on ScienceProfOnline.com
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If binary fission creates clones… …then: Why isn’t there just one type of bacteria? How do bacteria change (for example develop resistance to antibiotics)? Genetic Diversity in Prokaryotes Images: Binary Fission , JW Schmidt From the Virtual Microbiology Classroom on ScienceProfOnline.com
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Replication Mistakes: _________ of Genes Change in the nucleotide base sequence of a genome; rare. Almost always bad news, but... Rarely leads to a protein having a novel property that improves ability of organism and its descendants to survive and reproduce. Staph’s beta-lactamase gene is an example of a mutation that was advantageous. Images: Blinky & Bart, Matt Groening From the Virtual Microbiology Classroom on ScienceProfOnline.com
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_________ _________ Vertical gene transfer organisms replicate their genomes and provide copies to descendants. Passing on genes to descendants. Horizontal gene transfer – donor contributes part of genome to recipient that are not descendants; three types: Transformation Transduction Bacterial Conjugation Increasing Genetic Diversity in Prokaryotes Images: Binary Fission , JW Schmidt, Phylogenetic Tree , Eric Gaba, NASA Astrobiology institute. From the Virtual Microbiology Classroom on ScienceProfOnline.com
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___________________________________ When a recipient cell takes up DNA from the environment (such as DNA released from a dead organism). 1928 Frederick Griffith this process while trying to develop a vaccine for pneumonia caused by Streptococcus pneumoniae . Griffith worked with two strains of Strep . S Strain had a protective capsule & caused deadly pneumonia when injected into mice. R strain were mutants that could not make the protective capsule and did not cause deadly disease (because the white blood cells of the mice could easily destroy R strain cells). Increasing Genetic Diversity in Prokaryotes Images: Fredrick Griffith & Bobby , 1936, Coburn, Alvin F.; Pneumococcus , Giant Microbes; Rough (unencapsulated) and Smooth (encapsulated) Streptococcus pneumoniae , Wiki. From the Virtual Microbiology Classroom on ScienceProfOnline.com
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Meet the Microbe! _________________ ________________ Gram + cocci that occur in pairs or chains. Blood agar : alpha hemolytic under aerobic conditions and beta hemolytic under anaerobic conditions. 92 different strains , collectively called pneumococci, known to infect humans. Unencapsulated strains: Those with no capsule/glycocalyx are normal microbiota of lungs, sinuses and middle ear of 75% of people. Don’t cause disease. Encapsulated strains: Cells of virulent stains of S. pneumoniae are surrounded by a polysaccharide capsule which protects them from being digested by phagocytic white blood cells. The virulent strain can cause: - Pneumococcal pneumnia (causes 85% of pneumonia cases) - Sinusitis and otitis media - Bacterimia and Endocarditis Images: S. pneumoniae, PHIL #10864, #2896, #2113, #263 Note the “doughnut”-shape of Streptococcus pneumoniae bacterial colonies.
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