Bacterial cell (1)
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This document provides an overview of key differences between prokaryotic and eukaryotic cells, focusing on bacteria and archaea. It describes the basic structures of bacterial cells, including the cell envelope, cell wall, cell membrane, flagella, pili, capsules, and endospores. It highlights distinguishing features between gram positive and gram negative bacteria, such as cell wall composition and the presence of an outer membrane in gram negative bacteria.
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Bacterial cell (1)
- 1. 1 Dr. Alvin FoxDr. Alvin Fox
- 2. 2 Key WordsKey Words Prokaryotic Outer membrane Eubacteria (Bacteria) Periplasmic space Archaebacteria (Archaea) 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
- 4. 4 Prokaryotes (Bacteria)Prokaryotes (Bacteria) • EubacterEubacter "True" bacteria"True" bacteria – human pathogenshuman pathogens – clinical or environmentalclinical or environmental – one kingdomone kingdom • ArchaeaArchaea – Environmental organismsEnvironmental organisms – second kingdomsecond kingdom
- 5. 5 EukaryotesEukaryotes • Other cell-based life e.g.Other cell-based life e.g. – plantsplants – animalsanimals – fungifungi
- 6. 6 Prokaryotic Cell (versus EukaryoticProkaryotic Cell (versus Eukaryotic Cell)Cell) • Not compartmentalizedNot compartmentalized • Cell membranes lack sterols (e.g. cholesterol)Cell membranes lack sterols (e.g. cholesterol) • Single circular chromosomeSingle circular chromosome • RibosomesRibosomes - 70S- 70S - subunits- subunits • 30S (16S rRNA)30S (16S rRNA) • 50S (5S & 23S rRNA)50S (5S & 23S rRNA)
- 7. 7 Bacteria versusBacteria versus ArchaebacteriaArchaebacteria • EubacteriaEubacteria – peptidoglycan (murein)peptidoglycan (murein) – muramic acidmuramic acid • ArchaebacteriaArchaebacteria – pseudomureinpseudomurein – no muramic acidno muramic acid
- 8. 8 Bacteria versusBacteria versus ArchaebacteriaArchaebacteria • 16S rRNA16S rRNA – sequence differentsequence different
- 9. 9 Eukaryotic cell Prokaryotic cell Gram + Gram - Cell wallRough endoplasmic reticulum Mitochondria (e.g. animal) Nucleoid Nucleus Cell membrane Cytoplasm Flagellum Cell (inner) membrane Outer membrane Ribosomes Granule Cell wall Capsule Pili
- 10. 10 BacteriaBacteria • PlasmidsPlasmids • Extra-chromosomal DNA • multiple copy number • coding - pathogenesis factors - antibiotic resistance factors • bacterial replication
- 11. 11 The Cell EnvelopeThe Cell Envelope Gram PositiveGram Positive Gram NegativeGram Negative
- 12. 12 CytoplasmCytoplasm Oxidative phosphorylation occurs at cell membrane (since there are no mitochondria). Cell membrane The cell wall is outside of cell membrane – rigid, protecting cell from osmotic lysis. Cell Wall
- 13. 13 GRAM POSITIVEGRAM POSITIVE GRAM NEGATIVEGRAM NEGATIVE CytoplasmCytoplasm CytoplasmCytoplasm Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane Inner (cytoplasmic) membrane Outer Membrane Lipopolysaccharide Porin Braun lipoprotein Periplasmicspace
- 14. 14 Outer MembraneOuter Membrane Gram negativeGram negative bacteriabacteria • major permeability barriermajor permeability barrier • space between inner and outer membranespace between inner and outer membrane – periplasmic spaceperiplasmic space store degradative enzymesstore degradative enzymes • Gram positive bacteriaGram positive bacteria • no periplasmic spaceno periplasmic space
- 15. 15 GRAM NEGATIVEGRAM NEGATIVE CELL ENVELOPECELL ENVELOPE CytoplasmCytoplasm Inner (cytoplasmic) membrane Outer Membrane (Major permeability barrier) LipopolysaccharidePorin Braun lipoprotein Periplasmic space Degradative enzyme Periplasmic binding protein Permease
- 16. 16 CytoplasmCytoplasm Lipoteichoic acid Peptidoglycan-teichoic acid Cytoplasmic membrane GRAM POSITIVEGRAM POSITIVE CELL ENVELOPECELL ENVELOPE Degradative enzyme
- 17. 17 FLAGELLAFLAGELLA • Some bacteria are motileSome bacteria are motile • Locomotory organelles- flagellaLocomotory organelles- flagella • Taste environmentTaste environment • Respond to food/poisonRespond to food/poison – chemotaxischemotaxis
- 18. 18 • Flagella – embedded in cell membraneembedded in cell membrane – project as strandproject as strand – Flagellin (protein) subunitsFlagellin (protein) subunits – move cell by propeller like actionmove cell by propeller like action
- 19. 19 Axial filamentsAxial filaments – spirochetesspirochetes – similar function to flagellasimilar function to flagella – run lengthwise along cellrun lengthwise along cell – snake-like movementsnake-like movement
- 20. 20 Making Wall-less FormsMaking Wall-less Forms • Result from action of:Result from action of: – enzymes lytic for cell wallenzymes lytic for cell wall – antibiotics inhibiting peptidoglycan biosynthesisantibiotics inhibiting peptidoglycan biosynthesis • Usually non-viableUsually non-viable • Wall-less bacteria that don’t replicate:Wall-less bacteria that don’t replicate: – spheroplasts (with outer membrane)spheroplasts (with outer membrane) – protoplasts (no outer membrane).protoplasts (no outer membrane). • Wall-less bacteria that replicateWall-less bacteria that replicate – L formsL forms
- 21. 21 Naturally Wall-less GenusNaturally Wall-less Genus • MycoplasmaMycoplasma
- 22. 22 Pili (fimbriae)Pili (fimbriae) • hair-like projections of the cellhair-like projections of the cell • sexual conjugationsexual conjugation • adhesion to host epitheliumadhesion to host epithelium
- 23. 23 Capsules and slime layersCapsules and slime layers • outside cell envelopeoutside cell envelope • well defined: capsulewell defined: capsule • not defined: slime layer or glycocalyxnot defined: slime layer or glycocalyx • usually polysaccharideusually polysaccharide • often lost duringoften lost during in vitroin vitro cultureculture • protectiveprotective in vivoin vivo
- 24. 24 Endospores (spores)Endospores (spores) • Dormant cellDormant cell • Produced when starvedProduced when starved • Resistant to adverse conditionsResistant to adverse conditions - high temperatures- high temperatures - organic solvents- organic solvents • contain calcium dipicolinatecontain calcium dipicolinate • BacillusBacillus andand ClostridiumClostridium