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Classification
Why do we classify or separate different organism into groups?
Aristotle suggested plant and animal Kingdoms.
Why did this system work in 375 BC?
Why doesn’t it work today?
Modern day taxonomy relies on molecular, structural and evolutionary characteristics.
Examples –
Binomial Nomenclature –Each organism is assigned a two word Latin name. Genus, species
Homo sapiens , Homo sapiens
Bacillus anthracis , Bacillus anthracis
Classifications of Microbes
Prokaryoteo Bacteria
o Archea
Eukaryoteo Planta
o Animalia
o Fungi
o Protista
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Kingdom Animalia
Eukaryotic Multicellular No cell wall Consumer (mouth) Typically motile Examples –
Kingdom Planta
Eukaryotic Typically mulitcellular, some unicellular and colonial Cell wall – made of cellulose Producer No movement Examples –
Kingdom Fungi
Eukaryotic Unicellular or multicellular Cell walls – chitin Non-motile Consumer (no mouth), dead feeder, parasite Examples –
Domain Protista
Eukaryotic Unicellular and colonial Two distinct groups
o Plant – like characteristics Green Algae
Diatoms
Euglena
Dinoflagellates
Brown and red algae
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o Animal – like characteristics Ameboids
Flagellates
Ciliates
Sporozoans (no movement)
Domain Bacteria
Prokaryotic
Cell walls, peptidoglycan
Unicellular, some colonial
Parasite, dead feeder
May be motile
Examples –
Domain Archea –
Prokaryote
Unicellular or colonial
Non-motile
No cell wall
Specialized producer
Examples –
How do we classify plants and animals?
How is bacterial classification different from that of plants and animals?
What characteristics do we use to classify bacteria?
Cell wall composition
Morphology
o Shape
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Coccus
Bacillus
Spiral (vibrio, spirillum)
o Arrangement of cells
Diplo-
Strepto-
Staphylo-
Differential staining
o Gram stain
o Endospore stain
Oxygen requirements
DNA base pair comparison = A/T vs. C/G
Biochemical tests – what kind of media will they grow on?
Eukaryotic cell structure
No cell walls
Membrane bound organelles
o Mitochondria
o Nucleus
o Centriole
o Endoplasmic Reticulum
RER
SER
o Golgi Body
o Vacuole
o Peroxisome
Non membrane bound organelles
o Ribosome
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Prokaryotic Cell Structure
Outside the cell wall
o Glycocalyx
Negative staining technique
Capsule
Slime layer
o Flagella
Gives motility towards food (chemotrophic),
light (phototropyic)
Monotrichous
Lophotrichous
Amphitrichous
Peritrichous
o Fimbrae – provide attachment, G- bacteria
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o Pili – used to share DNA segments, a form of sexual
reproduction
o Cell wall – responsible for cell shape, controls osmotic
movement.
Made up of several materials, depending on
species.
Peptidoglycan typical component
Some bacteria have lipid in their cell wall,
special cell wall staining techniques
Gram staining procedure
Adhere to clean, dry slide.
Air dry
Flame, twice
Crystal violet
Gram’s iodine
Alcohol
Safranin (a counterstain)
Gram positive cells
Gram negative cells
Inside the cell wall
o Plasma membrane
Selectively permeable membrane
Fluid mosaic model
Hydrophobic unit
Hydrophilic unit
Proteins
Glycoproteins
o Cytoplasm
Cytosol + organelles
o DNA – one single, circular DNA
How to “stick the bacteria to the slide”
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o Plasmid – small, circular DNA
Replicates independent of DNA
Small number of genes (<10)
Carries information unnecessary to daily life
o Ribosome
site of protein synthesis
composed of rRNA + proteins
o Inclusions – reserve storage (fat, lipids, etc.)
o Endospore – in bacteria they are formed in response to
environmental stress, lack of nutrients, never
reproductive structures, mostly in G+
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