Title: Dr' Alvin Fox
1Bacterial cell, Lecture 32
Dr. Alvin Fox
2Key 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
3PROKARYOTES
EUKARYOTES
BACTERIA
ARCHAEA
4Prokaryotes (Bacteria)
- Eubacter "True" bacteria
- human pathogens
- clinical or environmental
- one kingdom
- Archaea
- Environmental organisms
- second kingdom
5Eukaryotes
- Other cell-based life e.g.
- plants
- animals
- fungi
6Prokaryotic 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)
7Bacteria versus Archaebacteria
- Eubacteria
- peptidoglycan (murein)
- muramic acid
- Archaebacteria
- pseudomurein
- no muramic acid
-
-
8Bacteria versus Archaebacteria
- 16S rRNA
- sequence different
9Eukaryotic cell
Prokaryotic cell
Gram
(e.g. animal)
Flagellum
Nucleoid
Cell wall
Cell membrane
Rough endoplasmic reticulum
Nucleus
Gram -
Cytoplasm
Mitochondria
10Bacteria
- Plasmids
- Extra-chromosomal DNA
- multiple copy number
- coding
- - pathogenesis factors
- - antibiotic resistance factors
- bacterial replication
11The Cell Envelope
Gram Stain
Gram Positive
Gram Negative
12Oxidative phosphorylation occurs at cell
membrane (since there are no mitochondria).
Cytoplasm
Cell Wall
Cell membrane
- The cell wall is outside of cell membrane
- rigid, protecting cell from osmotic lysis.
13GRAM POSITIVE
Lipoteichoic acid
Peptidoglycan-teichoic acid
Cytoplasmic membrane
Cytoplasm
GRAM NEGATIVE
Lipopolysaccharide
Porin
Outer Membrane
Braun lipoprotein
Periplasmic space
Inner (cytoplasmic) membrane
Cytoplasm
14Outer Membrane
- Gram negative bacteria
- major permeability barrier
- space between inner and outer membrane
- periplasmic space
- store degradative enzymes
- Gram positive bacteria
- no periplasmic space
15 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
16GRAM POSITIVE CELL ENVELOPE
Degradative enzyme
Peptidoglycan-teichoic acid
Lipoteichoic acid
Cytoplasmic membrane
Cytoplasm
17FLAGELLA
- Some bacteria are motile
- Locomotory organelles- flagella
- Taste environment
- Respond to food/poison
- chemotaxis
18- Flagella
- embedded in cell membrane
- project as strand
- Flagellin (protein) subunits
- move cell by propeller like action
-
19Axial filaments
- spirochetes
- similar function to flagella
- run lengthwise along cell
- snake-like movement
20Making Wall-less forms
- Result from action of
- enzymes lytic for cell wall
- antibiotics inhibiting peptidoglycan biosynthesis
- Usually non-viable
- Wall-less bacteria that dont replicate
- spheroplasts (with outer membrane)
- protoplasts (no outer membrane).
- Wall-less bacteria that replicate
- L forms
21Naturally Wall-less Genus
22Pili (fimbriae)
- hair-like projections of the cell
- sexual conjugation
- adhesion to host epithelium
23Capsules 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
24Endospores (spores)
- Dormant cell
- Produced when starved
- Resistant to adverse conditions
- - high temperatures
- - organic solvents
- contain calcium dipicolinate
- Bacillus and Clostridium
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