all kinds of shapes - budding yeasts - coccus - rods

- uses electrons, even shorter wavelength (0.005) - need to kill and/or stain the cells that you are viewing

lecture material Flashcards by erika lofton

microscopic

all kinds of shapes

budding yeasts
coccus
rods

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macroscopic

mushrooms
molds
fungi
algal blooms
biofilms

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Francesco Redi (spontaneous generation)

1668
maggots do not arise from rotting meat
no support for spontaneous generation

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John Needham (spontaneous generation)

1745
boiled broth, poured it into a flask and covered it; soon it was teeming with growth
supports spontaneous generation

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Spallanzani (spontaneous generation)

1765
4 treatments with broth
no support for spontaneous generation

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Louis Pasteur (golden age)

1861
Swan-necked flask
spontaneous generation does not occur

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Basi (germ theory)

1835

silkworm disease caused by a fungus

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Berkeley (germ theory)

1845
potato blight caused by a fungus
irish potato famine

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Semmelweis (germ theory)

1840s
child-bed fever was contagious
maternal death rate - 13-18% (1 in 5)
instituted washing hands between patients (rate decreased to 2%)

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Robert Koch (germ theory)

one specific microbial agent causes one specific disease

Koch’s postulates

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Schwann (microbial effects on matter)

1837

sugar —> alcohol (by yeilding yeast)

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Pasteur (microbial effects on matter)

1857-1860
beer
all fermentations are due to the activities of specific yeasts and bacteria

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Winogradsky (microbial effects on matter)

1892
microbes are involved in the cycling of nutrients in soil/aquatic environments
columns

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what is a species

organisms that do interbreeding naturally

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microbial species

lack obvious morphological differences

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traditional approaches for microbial species

staining
metabolic differences
biochemical tests

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genetic approaches for microbial species

based on DNA similarity

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light microscopy

uses visible light
magnification up to 1,000x
resolving power = .2 um

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bright field

light goes directly through specimen
dark specimen, bright background
used to view killed/stained microbes

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dark field

light does not go through specimen, but is refracted off
light specimen, dark background
used to view living, unstained microbes

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phase contrast

light is moved out of phase
slowing light down
enhances small differences
used to view internal structures in living microbes, especially eukaryotes

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fluorescence microscopy

UV light is used, shorter wavelength (100-400 nm)
invisible light
bright, fluorescent specimen, dark background
natural
used to view a specimen against a complex background

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electron microcopy

uses electrons, even shorter wavelength (0.005)

- need to kill and/or stain the cells that you are viewing

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transmission electron microscopy

transmitting electrons through a specimen
slice the cells really thin
view internal structures
RP = 0.2 nm

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scanning electron microscopy

- scan the surface with electrons - surface view of electrons - RP = 20 nm

prokaryotic cell: composition

H2O - 70% macromolecules - 26% small molecules - 4%

prokaryotic cell: cell sizes "average"

E. coli | 1 um x 2-6 um

prokaryotic cell: cell sizes "smallest"

0.2 um | mycoplasms

largest bacterium known

can see it with the naked eye about the size of a fruit fly Thiomargarita namibiensis

prokaryotic cells: internal structures - cytoplasm

80% water | 20% dissolved stuff

prokaryotic cell: internal structures - ribosomes

protein+RNA site of protein synthesis not organelles (not membrane bound)

prokaryotic cell: internal structures - nucleoid

- nuclear region - mostly DNA - circular chromosome

prokaryotic cell (some): internal structures - plasmids

- extrachromosomal DNA (DNA outside the chromosome) - circular - contain extra genes - antibiotic resistance, toxin production

prokaryotic cell (some): internal structures - endospores

- resting structures | - function: allows microbe to survive long term under adverse conditions

step one of endospores

sporulation (form spore) in response to some unfavorable environmental cue

step two of endospores

germination (spore -> vegetative cell) in response to some favorable environmental cue

plasma membrane: composition

1. phospholipids 2. proteins 3. bacteria have a bilayer (some archaea have a monolayer)

plasma membrane: simple diffusion

- small molecules move from high concentration to a low concentraiton - not very efficient - not often used - NO ATP - ex. CO2, O2

plasma membrane: osmosis

- solvents move from high concentration to low concentration (solvent is typically H2O) - high concentration of H2O to low concentration of H2O - NO ATP

plasma membrane: facilitated diffusion

- uses transporter proteins to move molecules across the membrane - ex. amino acids - important in eukaryotic cells, not prokaryotic - NO ATP

plasma membrane: active transport

- transport molecule against a concentration gradient - uses carrier proteins - organism can concentrate substances - requires ATP

plasma membrane: group translocation

- substance is chemically altered during movement - one way that glucose is brought into cell - requires ATP

cell wall

most prokaryotic cells have, with a few exceptions (mycoplasma)

cell wall: functions

1. shape 2. pathogenicity 3. protect from change in H2O pressure (keeps it from bursting)

Gram positive cells

- thick layers of peptidoglycan - single plasma membrane - techoic acid

techoic acids

toxic portions of gram positive cells

gram negative cells

- thin layer of peptidoglycan - lipopolysaccharide - two plasma membranes (inner and outer)

lipopolysaccharide (LPS)

toxic portion of gram (-) cells

archaea (in relation to gram (-)/(+) cells)

no peptidoglycan | pseudomurein

pseudomurein

similar to peptidoglycan

only ______ can make peptidoglycan

bacteria

budding yeasts - shape

spheres

antoni van Leeuwenhoek

1673 | first to see microbes

Lister (germ theory)

1867 phenol (listerine) aseptic surgery

3 domain system

- bacteria, archaea, and euckarya | - how tree of life is produced

resolution

the ability to see two things that are close together as discrete objects

shorter wavelength = _____ resolution

better

refraction

bending of light as it passes from one medium to another of different density

macromolecules

proteins carbohydrates ribosomes

prokaryotic cell: cell shapes - coccus

spheres

diplococci

pairs of spheres

streptococci

chains of spheres

staphylococci

clusters of spheres

bacillus

rods

streptobacilli

chains of rods

diplobacilli

pairs of rods

vibrio (spirals)

curved

spirochete

spiral

plasma membrane: function

- retains the cytoplasm - site of crucial metabolic processes - contains receptor molecules