Microbiology lab midterm review

Microbiology Lab Midterm Review
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Microbiology Lab Midterm Review Wednesday, October 08, 2008 10:41 PM Experiment 1- Media Preparation and Sterilization 1. Solid medium contains agar (from red algae) Melts @ 100°C, Solidifies @ 40-42°C 2. Types Plate - isolation Slant - maintenance Broth - liquid Deep – anaerobic growth 3. Complex medium – composed of digests of chemically undefined substances such as yeast and meat extracts 4. Defined medium – medium whose precise chemical composition is known Sterilization : killing or removal of all living organisms 5. Autoclave: 121°C (for media, glass) 6. Dry heat: flaming, hot air (for loops, glass) 7. Filtration: for heat-sensitive liquids (antibiotics) 8. Radiation: UV, gamma rays (for surfaces) 9. Cold sterilization: ethylene oxide (for heat-sensitive materials) 10. Experiment 2- Culturing Microorganisms from the environment 1. Minority of microorganisms are pathogenic- disease causing agent 2. Nosocomial means hospital-acquired Purpose : This experiment will demonstrate the ubiquitous nature of microorganisms. Materials needed: 3. 1 Trypticase Soy (TS) broth 4. 2 TS agar plates 5. 2 sterile swabs Experiment 3- Hand Washing 6. Resident (normal) microbiota/flora occur naturally on or in body 7. Transient flora temporary on body, can’t grow on skin because skin is too dry and acidic 8. Nosocomial infection hospital-acquired infection 9. Infectious dose number of microorganisms required to establish an infection
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Purpose Experiment 4- Colony Morphology 10. colony - a group of genetically identical bacteria, arising from a single cell on an agar plate 11. colony morphology - colony characteristics; see next slide 12. contaminant - an unwanted organism which has been accidentally introduced into the culture 13. Purpose : To observe the colony morphology of several organisms and become familiar with the terms used to describe colony morphology 14. Organism Color Colony shape Margin shape Elevation Optical properties Surface charact-eristic Escherichia coli Beige Round Smooth Flat/ convex translucent Shiny Bacillus cereus White Rhizoid Lobate/ filament Flat opaque Dull Micrococcus luteus Yellow Round Smooth Convex opaque Shiny Saccharomyces cerevisiae White Round Smooth Convex/ umbonate opaque Shiny Streptomyces coelicolor Purple/ white Irregular/ round Smooth/ lobate Flat opaque Dull Serratia marcescens red round smooth convex opaque shiny Experiment 5- Asceptic Technique See p. 20-21 for proper technique Experiment 6- Pure Culture 15. Pure culture - one that contains only one kind of microorganism; an isolated colony is one example of this 16. Streak plate - technique for diluting bacteria on agar plates; can be used to isolate individual bacteria from a mixture Purpose : To isolate a pure culture (in the form of an isolated colony) from a mixed culture using the dilution technique known as streak plating 17. Important to use proper aseptic technique in lab to avoid contaminants
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