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Bacterial cell, Lecture 32. Dr. Alvin Fox. Archaebacteria . ( Archaea ). Key Words. Prokaryotic. Outer membrane . Eubacteria ( Bacteria ) . Periplasmic space. Oxidative phosphorylation . Eukaryotic. Spheroplast/protoplast . Plasmid.

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key words

Archaebacteria

(Archaea)

Key Words

Prokaryotic

Outer membrane

Eubacteria (Bacteria)

Periplasmic space

Oxidative phosphorylation

Eukaryotic

Spheroplast/protoplast

Plasmid

Flagella

Chromosome

Chemotaxis

Ribosome

Axial filament

Peptidoglycan (murein, mucopeptide)

Periplasmic binding protein

Gram stain

Permeases

Gram negative

Storage Granules

Gram positive

Pili (fimbriae)

Cell envelope

Capsule (slime layer, glycocalyx)

Cell membrane

Endospore (spore)

Cell wall

prokaryotes

EUKARYOTES

PROKARYOTES

BACTERIA

ARCHAEA

prokaryotes bacteria
Prokaryotes (Bacteria)
  • Eubacter "True" bacteria
    • human pathogens
    • clinical or environmental
    • one kingdom
  • Archaea
    • Environmental organisms
    • second kingdom
eukaryotes
Eukaryotes
  • Other cell-based life e.g.
  • plants
  • animals
  • fungi
prokaryotic cell versus eukaryotic cell
Prokaryotic Cell (versus Eukaryotic Cell)
  • Not compartmentalized
  • Cell membranes lack sterols (e.g. cholesterol)
  • Single circular chromosome
  • Ribosomes

- 70S

- subunits

      • 30S (16S rRNA)
      • 50S (5S & 23S rRNA)
bacteria versus archaebacteria
Bacteria versus Archaebacteria
  • Eubacteria
    • peptidoglycan (murein)
    • muramic acid
  • Archaebacteria
    • pseudomurein
    • no muramic acid
bacteria versus archaebacteria8
Bacteria versus Archaebacteria
  • 16S rRNA
    • sequence different
slide9

Eukaryotic cell

Prokaryotic cell

Gram +

(e.g. animal)

Flagellum

Nucleoid

Cell membrane

Cell wall

Rough endoplasmic

reticulum

Nucleus

Gram -

Pili

Granule

Capsule

Cytoplasm

Cell (inner) membrane

Outer membrane

Ribosomes

Mitochondria

Cell wall

bacteria
Bacteria
  • Plasmids
    • Extra-chromosomal DNA
    • multiple copy number
    • coding
      • - pathogenesis factors
    • - antibiotic resistance factors
    • bacterial replication
slide11

The Cell Envelope

Gram Stain

Gram Positive

Gram Negative

slide12

Oxidative phosphorylation occurs at cell membrane

(since there are no mitochondria).

Cell Wall

Cytoplasm

Cell membrane

  • The cell wall is outside of cell membrane
    • rigid, protecting cell from osmotic lysis.
slide13

GRAM POSITIVE

Lipoteichoic acid

Peptidoglycan-teichoic acid

Cytoplasmic membrane

Cytoplasm

GRAM NEGATIVE

Lipopolysaccharide

Porin

Outer Membrane

Braun lipoprotein

Periplasmic space

Inner (cytoplasmic) membrane

Cytoplasm

outer membrane
Outer Membrane
  • Gram negative bacteria
  • major permeability barrier
  • space between inner and outer membrane
    • periplasmic space
      • store degradative enzymes
  • Gram positive bacteria
  • no periplasmic space
gram negative cell envelope
GRAM NEGATIVE CELL ENVELOPE

Outer Membrane

(Major permeability barrier)

Lipopolysaccharide

Porin

Braun lipoprotein

Periplasmic space

Degradative enzyme

Periplasmic binding protein

Permease

Inner (cytoplasmic) membrane

Cytoplasm

gram positive cell envelope
GRAM POSITIVE CELL ENVELOPE

Degradative enzyme

Peptidoglycan-teichoic acid

Lipoteichoic acid

Cytoplasmic membrane

Cytoplasm

flagella
FLAGELLA
  • Some bacteria are motile
  • Locomotory organelles- flagella
  • Taste environment
  • Respond to food/poison
    • chemotaxis
slide18

Flagella

    • embedded in cell membrane
    • project as strand
    • Flagellin (protein) subunits
    • move cell by propeller like action
axial filaments
Axial filaments
  • spirochetes
  • similar function to flagella
  • run lengthwise along cell
  • snake-like movement
slide20

Making Wall-less forms

  • Result from action of:
    • enzymes lytic for cell wall
    • antibiotics inhibiting peptidoglycan biosynthesis
  • Usually non-viable
  • Wall-less bacteria that don’t replicate:
    • spheroplasts (with outer membrane)
    • protoplasts (no outer membrane).
  • Wall-less bacteria that replicate
    • L forms
slide22

Pili (fimbriae)

  • hair-like projections of the cell
  • sexual conjugation
  • adhesion to host epithelium
slide23

Capsules and slime layers

  • outside cell envelope
  • well defined: capsule
  • not defined: slime layer or glycocalyx
  • usually polysaccharide
  • often lost during in vitro culture
  • protective in vivo
endospores spores
Endospores (spores)
  • Dormant cell
  • Produced when starved
  • Resistant to adverse conditions
  • - high temperatures
  • - organic solvents
  • contain calcium dipicolinate
  • Bacillus and Clostridium