Classification
Why do we classify or separate different organism into groups?
Aristotle suggested plant and animal Kingdoms.
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Why did this system work in 375 BC?
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Why doesn’t it work today?
Modern day taxonomy relies on molecular, structural and evolutionary
characteristics.
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Examples –
Binomial Nomenclature –Each organism is assigned a two word Latin
name. Genus, species
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Homo sapiens, Homo sapiens
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Bacillus anthracis, Bacillus anthracis
Classifications of Microbes
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Prokaryote
o Bacteria
o
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Archea
Eukaryote
o Planta
o
Animalia
o
Fungi
o
Protista
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Kingdom Animalia
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Eukaryotic
Multicellular
No cell wall
Consumer (mouth)
Typically motile
Examples –
Kingdom Planta
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Eukaryotic
Typically mulitcellular, some unicellular and colonial
Cell wall – made of cellulose
Producer
No movement
Examples –
Kingdom Fungi
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Eukaryotic
Unicellular or multicellular
Cell walls – chitin
Non-motile
Consumer (no mouth), dead feeder, parasite
Examples –
Domain Protista
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Eukaryotic
Unicellular and colonial
Two distinct groups
o Plant – like characteristics
 Green Algae
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Diatoms
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Euglena
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Dinoflagellates
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Brown and red algae
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o
Animal – like characteristics
 Ameboids
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Flagellates
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Ciliates
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Sporozoans (no movement)
Domain Bacteria
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Prokaryotic
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Cell walls, peptidoglycan
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Unicellular, some colonial
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Parasite, dead feeder
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May be motile
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Examples –
Domain Archea –
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Prokaryote
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Unicellular or colonial
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Non-motile
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No cell wall
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Specialized producer
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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?
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Cell wall composition
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Morphology
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o
o
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Shape
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Coccus
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Bacillus
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Spiral (vibrio, spirillum)
Arrangement of cells
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Diplo-
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Strepto-
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Staphylo-
Differential staining
o
Gram stain
o
Endospore stain
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Oxygen requirements
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DNA base pair comparison = A/T vs. C/G
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Biochemical tests – what kind of media will they grow on?
Eukaryotic cell structure
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No cell walls
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Membrane bound organelles
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o
Mitochondria
o
Nucleus
o
Centriole
o
Endoplasmic Reticulum
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RER
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SER
o
Golgi Body
o
Vacuole
o
Peroxisome
Non membrane bound organelles
o
Ribosome
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Prokaryotic Cell Structure
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Outside the cell wall
o
o
Glycocalyx
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Negative staining technique
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Capsule
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Slime layer
Flagella
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Gives motility towards food (chemotrophic),
light (phototropyic)
o
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Monotrichous
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Lophotrichous
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Amphitrichous
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Peritrichous
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.
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Made up of several materials, depending on
species.
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Peptidoglycan typical component
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Some bacteria have lipid in their cell wall,
special cell wall staining techniques
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Gram staining procedure
How to “stick the
bacteria to the slide”
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Adhere to clean, dry slide.
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Air dry
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Flame, twice
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Crystal violet
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Gram’s iodine
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Alcohol
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Safranin (a counterstain)
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Gram positive cells
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Gram negative cells
Inside the cell wall
o
o
Plasma membrane
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Selectively permeable membrane
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Fluid mosaic model
Hydrophobic unit
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Hydrophilic unit
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Proteins
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Glycoproteins
Cytoplasm
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o
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Cytosol + organelles
DNA – one single, circular DNA
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o
o
Plasmid – small, circular DNA
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Replicates independent of DNA
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Small number of genes (<10)
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Carries information unnecessary to daily life
Ribosome
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site of protein synthesis
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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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