Topic #1 Flashcards
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Robert Hooke
First to see microbes - saw fruiting structure of mold. Published in Micrographia in 1665
Antony van Leeuwenhoek
Saw “wee animalcules,” bacterial cells, in 1676. Used 300x magnification with Dark-Field.
Francesco Redi
Meat & Maggots experiment to disprove Spontaneous Generation in Macrobes
Spontaneous Generation
The first question of Microbiology. Can living matter arise from non-living matter?
Louis Pasteur & Spontaneous Generation
Gun-Cotton filters to show microbes were in the air. Swan-Neck flask trapped microbes while still allowing “good air” into the broth:::No Spontaneous Generation in microbes.
Louis Pasteur & Diseases
Worked in silkworm protozoans. Rabies Vaccine (Joseph Meister). Cholera. Pastuerization started with wine spoilage.
Joseph Tyndall
Tyndallization - Discontinuous heating lead to endospores - answered the “how long do you heat it for” question.
Ferdinand Cohn
Proved endospores existed at same time as Tyndall
Agostino Bassi
Proved a silkworm disease came from a fungus in 1835.
Germ Theory of Diseases
Question #2 - Can microbes cause diseases in animals? Bassi was the first to answer this fundamentally, others soon followed.
Miles Berkeley
Proved existence of Potato Blight Fungus. Got rich because it was important
Joseph Lister
Pushed for cleaner hospital practice which in turn lowered death rates - Listerine named in honor of him
Robert Koch
ID’d Anthrax & TB bacteria. Postulates for Germ Theory proved that it existed. Developed solid media - agar not gelatin
Koch’s Postulate #1
Suspected pathogen has to be present in 100% of cases of disease and 0% in healthy organisms.
Koch’s Postulate #2
Suspected Pathogen must be grown in pure culture (spurred agar media)
Koch’s Postulate #3
Cells from pure culture put into healthy animal must cause disease
Koch’s Postulate #4
Suspected Pathogen must be reisolated & same as original pure culture
Fannie Hesse
Koch’s lab: Wife of lab assistant who suggested Agar as the solid media over gelatin
Richard Petri
Koch’s lab assistant who developed Petri Dish
Edward Jenner
Noticed maids w/cowpox never got smallpox. Infected farmboy with cowpox, then smallpox; he didn’t get smallpox. First (attenuated) vaccine. 1798.
Martinus Beijerinck
Enrichment Culture technique - isolation done by selective nutrient growth. Also discovered TMV (Tobacco Mosaic Virus) which was beginning of Virology. Nitrogen Fixers.
Sergei Winogradsky
Microbial rxns in soil - without real media still occur. Chemolithotrophy. Autotrophy.
Chemolithotrophy
Bacteria that can gain energy from non-organics
Autotrophy
Taking fully oxidized carbon and converting them to reduced carbs
Attenuated Vaccines
Using live things to vaccinate against other diseases. Pasteur & Meister (Rabies); Jenner (Smallpox)
Fermentation
Microbial because spontaneous sometimes? Yeast & lactic acid
Pasteurization
Partial heating to prevent wine spoilage
Microbial Ecology
Showing microbial interaction w/environments
Beijerinck with Enrichment Cultures of soil/water & TMV.
Winogradsky with energy from non-organic sources.
Types of Microscopes
4 Light: Bright-Field, Phase-Contrast, Dark-Field, Flourescence.
2 Electron: Transmission (TEM), Scanning (SEM)
Refraction
Slowing & Bending of light
Focus issues with no lenses
Stuff gets blurry when you get close. Looking for shorter Focal Length.
Compound Microscopes
Microscopes with 2+ lenses - solves 1-lens problem (only 10-15x per lens).
Focal Point
The thing you’re focusing at
Focal Length
The distance between Focal Point and Lens
Parfocal
Picture being in focus for multiple lenses. Expen$ive
Bright-Field Microscopes & Advantages
Ocular with 10x lenses; multiple objective lenses on turret. Field is bright. Intermediate image between lenses.
Resolution Description
The ability to distinguish two objects from one another. How close can these two things be and I can tell the difference between them?
Resolution Distance Formula
d=(.5λ)/Numerical Aperture
d= minimum distance two objects can be apart to tell the difference.
Numerical Aperture
Measures light-gathering ability. Shows refractive Index. Works best at low λ.
Staining
Coloration of microbes to avoid the issue with light passing through clear microbes. Works great on Bright-Field.
Heat Fixation
Attaches microbes to slide using heat (&/or chemicals). Inactivates stray enzymes on the slide.
Gram Staining Steps
- Crystal Violet - All Cells Purple
- Iodine - Mordant for some cells
- Alcohol Decolorization - washes off purple from Gram Negs (where mordant failed)
- Safranin counterstain - makes now clear Gram Negs pink/red
Chromophore Dyes
Dyes that absorb light
Charged Dyes
Basic Dyes have + charges (more common)
Acidic Dyes have - charges
Differential (i.e. Gram) Staining
To differentiate between specific attributes of cells. Gram- peptidoglycan levels.
Phase-Contrast Microscope & Advantages
Uses Condenser to focus light. We only see the light reflected by the cell. Looks like dark-fieldish.
No Staining, fixation req’d. Useful for long, thin stuff.
(van Leeuwenhoek)
3-D Image Microscopy
3 Types:
- Differential Intereference Contrast
- Atomic Force
- Confocal Scanning Laser
Transmission Electron Microscope
Electron Beam passes directly through the specimen in a vacuum (to keep air/stuff out).
Lenses = magnets to focus beam
Electrons = Heated Tungsten Filament
Dark on light background. Detection comes from film, not your eyeball.
Works b/c λ is shorter than a photon’s; better resolution. Requires really thin sections of specimen.
Staining in EM
Aim to enhance electron density of specimen.
Heavy Metal Salts - Good at deflecting electrons (uranyl acetates)
+ Stains: can see internal structures b/c increased e- density
- Stains: if background is stained
Platinum Shadowing
Coat specimen in platinum - way better electron density for reflection
Scanning EM
Used for shapes & surfaces
Usually coat specimen with gold to get 3D fashion
Scan beam @ 45 degree angle->Software constructs image from input.
Fluorescence Microscope
Plays off of biological fluorescence. Microscope emits excitation wavelength of light=passes through to light tube. Used sparingly - sometimes in diagnostics b/c antibodies have specific dyes esp. in mixed
