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

  • Prokaryote
  • Bacteria
  • Archea
  • Eukaryote
  • Planta
  • Animalia
  • Fungi
  • Protista

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 –

DomainProtista

  • Eukaryotic
  • Unicellular and colonial
  • Two distinct groups
  • Plant – like characteristics
  • Green Algae
  • Diatoms
  • Euglena
  • Dinoflagellates
  • Brown and red algae
  • 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
  • Shape
  • Coccus
  • Bacillus
  • Spiral (vibrio, spirillum)
  • Arrangement of cells
  • Diplo-
  • Strepto-
  • Staphylo-
  • Differential staining
  • Gram stain
  • 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
  • Mitochondria
  • Nucleus
  • Centriole
  • Endoplasmic Reticulum
  • RER
  • SER
  • Golgi Body
  • Vacuole
  • Peroxisome
  • Non membrane bound organelles
  • Ribosome

Prokaryotic Cell Structure

  • Outside the cell wall
  • Glycocalyx
  • Negative staining technique
  • Capsule
  • Slime layer
  • Flagella
  • Gives motility towards food (chemotrophic), light (phototropyic)
  • Monotrichous
  • Lophotrichous
  • Amphitrichous
  • Peritrichous
  • Fimbrae – provide attachment, G- bacteria
  • Pili – used to share DNA segments, a form of sexual reproduction
  • 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
  • Plasma membrane
  • Selectively permeable membrane
  • Fluid mosaic model
  • Hydrophobic unit
  • Hydrophilic unit
  • Proteins
  • Glycoproteins
  • Cytoplasm
  • Cytosol + organelles
  • DNA – one single, circular DNA
  • Plasmid – small, circular DNA
  • Replicates independent of DNA
  • Small number of genes (<10)
  • Carries information unnecessary to daily life
  • Ribosome
  • site of protein synthesis
  • composed of rRNA + proteins
  • Inclusions – reserve storage (fat, lipids, etc.)
  • Endospore – in bacteria they are formed in response to environmental stress, lack of nutrients, never reproductive structures, mostly in G+

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