Presentation on theme: "A Brief History of Microbiology"— Presentation transcript:
1A Brief History of Microbiology Chapter 1A Brief History of Microbiology
2Chapter 1 Assignment Note: Homework assignments are due at the exam Multiple Choice 1-10Matching 1-12Concept MapList Steps of Scientific Method in order and describe each oneDiscuss Pasteur’s experiment with the swan necked flasks investigating spontaneous generation. How does it exemplify the first 4 steps of the scientific method. Be specific. What was the experimental group? Control group? Result?
16Figure 1.8 An immature stage of a parasitic worm in blood Red blood cellLooks like Trypanosoma (parasite of mammals that causes sleeping sickness)
17Figure 1.9 Viruses infecting a bacterium Virus: tiny infectious acellular agent with nucleic acid surrounded by proteinaceous capsomeres that form a covering called a capsidViruses assembling inside cell
27Figure 1.12 Pasteur’s experiments with “swan-necked” flasks Steam escapes from open end of flask.Dust from air settles in bend.Air moves in and out of flask.MonthsInfusion is heated.Infusion sits; no microbes appear.Infusion remains sterile indefinitely.
30Figure 1.13 The scientific method ObservationsQuestionRepeatExperimental data support hypothesisAccept hypothesisTheory or lawExperiment, including control groupsHypothesisObservationsReject hypothesisExperimental data do not support hypothesisModify hypothesisModified hypothesis
32Figure 1.14 Pasteur's application of the scientific method Observation:Fermenting grape juiceMicroscopic analysis shows juice contains yeasts and bacteria.HypothesisExperimentObservationConclusionDay 1: Flasks of grape juice are heated sufficiently to kill all microbes.Day 2I.Spontaneous fermentation occurs.No fermentation; juice remains free of microbesReject hypothesis I.Flask is sealed.II.Air ferments grape juice.No fermentation; juice remains free of microbesReject hypothesis II.Flask remains open to air via curved neck.III.Bacteria ferment grape juice into alcohol.Bacteria reproduce; acids are produced.Modify hypothesis III; bacteria ferment grape juice into acids.Juice in flask is inoculated with bacteria and sealed.IV.Yeasts ferment grape juice into alcohol.Yeasts reproduce; alcohol is produced.Accept hypothesis IV; yeasts ferment grape juice into alcohol.Juice in flask is inoculated with yeast and sealed.