Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Module 2a cytology & physiology


Published on

dr. lu2

Published in: Education, Technology
  • Be the first to comment

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?