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Module 2a cytology & physiology

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dr. lu2

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Module 2a cytology & physiology

  1. 1. Bacterial Cytology & Physiology Bacterial Taxonomy Parts of a bacterial cellSpecialized structures in bacteria
  2. 2. Taxonomical Ladderx Kingdom Monerax Phylum x Kingdom Plantaex Class x Kingdom Animaliax Order x Kingdom Protistax Family x Kingdom Fungix Genus x Kingdom Monerax Specie - Type & Strain
  3. 3. New Classification:x Carl Woese – based on cellular organization (Domain above Kingdom) x Bacteria– cell wall w/ peptidoglycan x Archaea – cell walls, if present lack peptidoglycan x Eukarya – Protista, Fungus, Plants, Animals
  4. 4. Characters used to classify Bacteriax Morphology- cell x Percentage of DNA shapes & struc. base pairsx Biochemistry & x DNA sequence Physiology - condi- x DNA hybridization tions & process x sequence of aminox Serology - FAT & acids in proteins slide agglutination x protein profilesx Phage typing x sequence of rRNA
  5. 5. Prokaryote VS. Eucaryote
  6. 6. Procaryotesx appendages: pili, x presence of flagella, axial filaments plasma membrane in spirochetes x undiff. cytoplasmx Usually glycocalyx is x non-membrane present bound organellesx outer membrane present x 1 circular DNA in gram (-) x binary fissionx cell wall in all eubacteria x 1 to few u
  7. 7. Eucaryotesx different flagella from x cytoskeleton & procaryotes cytoplasmic streamingx very few has x membrane bound glycocalyx organellesx no outer memb. x paired chromosomex no cell wall x mitosis & meiosisx plasma membrane- x no endospores phospholipid bilayer x > than 10 u
  8. 8. Bacterial Cytologyx Structures external to the cell wallx The cell Wallx Structures internal to the cell wallx General Structuresx Specialized structures
  9. 9. External to the cell wall:x Glycocalyx – sugar coat x Viscous, gelatinous polymer on the external of the cell, composed of polysaccharide, polypeptide or bothx Capsule – If Glycocalyx is organized and firmly attached to the cell wall, capsule is formed x Determines virulence of the cell x Negative Staining
  10. 10. x Slime layer - If the substance is unorganized & loosely attached to cell wall.x EPS ( Extracellular polysaccharide ) – x Glycocalyx made of sugar- enables the bacteria to attach to various surfaces in the natural environment in order to survive.x Flagella/Flagellum ( whip ) x Long filamentous appendages that propel bacteria
  11. 11. Arrangements of flagella:x Monotrichous – single polarx Amphitrichous – tuft at each endx Lophotricous – 2 or more at one endx Peritrichous – entire cellx Atricous – no flagellax Flagellar rotation depend on cells continuous generation of energyx Flagellar motion – run, swim, tumble, swarm
  12. 12. x Axial Filaments x Unique in spirochetes, also called endoflagella, which are bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell. x Propulsion causes spiral motion or corkscrew movement
  13. 13. Fimbriae & Pili:x Fimbriae/Fimbria x can occur at the poles of the cell or evenly distributed all over x Functions for cell attachment/ in the absence colonization cannot happen so no disease ensuesx Pili/Pilus x Longer than fimbriae, only 1 – 2 per cell x Preparation for DNA transfer – sex pili
  14. 14. The Cell Wallx Complex, semi rigid structure responsible for the shape of the cellx Composed of peptidoglycan (also known as murein) made up of NAG ( N- acetylglucosamine) and NAM (N-acetyl muramic acid). x Structures on the disaccharide portion is repeating.
  15. 15. Gram + & - cell walls:x Most gram (+) bacteria have many layers of peptidoglycan in the cell wall forming a thick rigid structure while gram (-) only contain 1 thin layer of peptidoglycan.x Gram (+) contains teichoic acid consisting primarily of an alcohol & phosphate x Lipoteichoic Acid x Wall teichoic Acidx Gram (-) cell walls are susceptible to mechanical breakage because they contain only small amount of peptidoglycan
  16. 16. Internal to the Cell Wall:x Plasma Membrane/Bacterial Membranex Cytoplasmx The Nucleusx Ribosomesx Inclusions x Metachromatic granules x Magnetosomesx Endospores
  17. 17. Bacterial Membranex Functions: x Demonstrated by: x osmosis & x Plasmolysis permeability x Stain - Victoria x cell division Blue x primer for x Isolation - Diff. biosynthesis centrifuge x site of Ag x Ultrathin determinant sections
  18. 18. Bacterial shapes & arrangementsx Coccus - x Spirillus x single, diplo, x wavy, corkscrew, tetrad, sarcinae, comma-shaped strepto , staphylo. x Spiral bacteria mayx Bacillus - have 1 or more x single, diplo, twists strepto
  19. 19. Additional Shapesx Star shaped cells – Genus Stellax Rectangular flat cells – halophilic Genus Haloarculax Triangular shaped cells
  20. 20. Basis of Shape:x Shape of the bacterium is primarily dependent on heredity.x Generally bacteria are monomorphic, maintain 1 single shapex Due to environmental conditions, some bacteria tend to become pleomorphic which makes identification difficult. I.e. Rhizobium & Corynebacterium
  21. 21. Trivia:x Is coccobacilli a coccus or a bacilli? Maybe both or neither of the two?x Why do bacillus not have tetrads or clusters?

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