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Prokaryotic profiles

Prokaryotic profiles. When did prokaryotes first appear?. What are the basic differences?. How do prokaryotes compare in size with other microorganisms?. How do I describe their shapes? . Is a species always the same shape?. Generally, yes Monomorphic however, environment can alter

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Prokaryotic profiles

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  1. Prokaryotic profiles

  2. When did prokaryotes first appear?

  3. What are the basic differences?

  4. How do prokaryotes compare in size with other microorganisms?

  5. How do I describe their shapes?

  6. Is a species always the same shape? • Generally, yes • Monomorphic • however, environment can alter • Some are pleiomorphic Photo from: uhavax.hartford.edu/bugl/Yersinia-pestis.jpg

  7. The parts Starting from the outside and working inward

  8. What’s outside the cell wall? • Glycocalyx • Carbohydrates and/or peptides • Viscous • Can protect bacterium • Some help cells attach • Teeth: Streptococcus mutans • Capsule • Organized • Firmly attached to cell wall • Slime layer • Unorganized • Loosely attached

  9. What are flagella? • Singular = __________ • Monotrichous • Amphitrichous • Lophotrichous • Peritrichous

  10. What do flagella do? • Run and tumble • Swarming • Allow for taxis • Chemotaxis • Phototaxis • dancing bacteria!

  11. What are axial filaments? • AKA periplasmic flagella • Fibril bundles that spiral around cell

  12. What’s the difference between fimbriae and pili? • Found primarily on gram-negative bacteria • For attachment, not movement • Pilin protein • Fimbriae (fimbria, singular) • Attachment • E.g. to mucosal membranes • Pili (pilus, singular) • For DNA exchange only

  13. What’s in the cell wall? • Peptidoglycan (PPG) • AKA murein • NAG-NAM disaccharide • NAG = N-acetyleglucosamine • NAM = N-acetylemuramic acid • Lysozyme disrupts NAG-NAM bond • If lysis doesn’t occur, cell is called a protoplast • Linked with tetrapeptide • Penicillin disrupts  lysis • penicillin killing cells

  14. What’s in the cell wall? • Gram positive bacteria • Many PPG layers • Teichoic acids • Different types • Used for antigenic specificity tests

  15. What’s in the cell wall? • Gram negative bacteria • One or few PPG layer(s) • Outer membrane: lipopolysaccharides (LPS), lipoproteins, phospholipids • Periplasm separates LPS from the PM (PPG is in periplasm) • Provides barrier to some antibiotics, digestive enzymes • Porins allow for access into cell • LPS used for specific antigen tests to I.D. species

  16. What does a side-by-side comparison look like?

  17. More comparison

  18. How does this relate to gram staining? • Hint: What does the LPS layer covering the gram negative cell do to it?

  19. What are atypical cell walls? • Mycoplasma • Smallest known independent bacteria • No cell walls • Often mistaken for viruses • PM has sterols to prevent lysis • Mycobacteria • Mycolic acid in cell wall • Hydrophobic • Acid-fast stain identifies • Tuberculosis, leprosy • Archaea • Some have cell walls but not with PPG • Pseudo-murein Mycoplasm pneumoniae

  20. What happens if the cell wall is damaged? • Lysozyme lyses gram positive, but usually does not harm gram negative to the same extent • Why? • Protoplast: gram positive • Spheroplast: gram negative • Osmostic lysis • If placed in a hypotonic environment

  21. What’s inside the cell wall? • Plasma membrane • Phospholipidbilayer • Fluid mosaic theory • Segregates DNA during binary fission • Secretes enzymes to make PPG, teichoic acid • ATP production • Selective permeable membrane… • Active vs. passive transport

  22. What kinds of passive transport exist? • Simple diffusion • For small, lipid-soluble substances • Osmosis • Water movement via diffusion • Happens whenever difference in concentration across PM • Note: water often moves because solutes can’t • Because PM is only semi-permeable Simple diffusion

  23. What do you think will happen?  Left side increases with water Right side increases with water No net movement of water Click here to show what actually happens: answer animation

  24. What is osmosis? • Water concentration depends on number of solutes in it • Hypertonic • Isotonic • Hypotonic • Water moves down its concentration gradient until osmolarity is equal

  25. 10% glucose 20% glucose 10% glucose Distilled water What do you think will happen? For each, choose from A. No net change B. cell swells C. cell shrinks

  26. What is facilitated passive diffusion? • Protein-assisted diffusion • Transporters or carriers • Amino acids, glucose • Channels (AKA “pores”) • Most are gated (usually closed)

  27. What is active transport? • Movement of solute against gradient • Can you think of examples of where this might happen in your body? • Requires energy b/c moving against gradient • From ATP • Proteins sometimes called “pumps”

  28. What is group translocation? • Type of active transport • Only in prokaryotes • Chemically altered as it is pulled across PM into cell • Once inside, cannot exit • E.g. glucose phosphorylation • Animation

  29. What is the cytoplasm? • Eukaryotes • Cytosol + organelles • Prokaryotes: all stuff inside cell • 80% water + nuclear area, ribosomes, inclusions (storage areas)

  30. What is the nuclear area? • AKA nucleoid • Circular, double-stranded DNA • Called bacterial chromosome • Plasmid • Also double-stranded DNA • Independent replication • Associated with PM proteins • Can gain or lose without killing cell • Can provide resistance to antibiotics, etc.

  31. What are ribosomes? • Manufacture proteins • Two subunits • Each with proteins and rRNA • 70S ribosomes (smaller than eukaryotes) • 50S and 30S subunits • Eukaryotes = 80S ribosomes (60S + 40S)

  32. What are inclusions? • Storage areas • Metachromatic granules • Collectively called volutin • Phosphate reserve for making ATP • Polysaccharide granules • Iodine stain shows these • Others with • Lipids, sulfur granules, etc. • Magnetosomes: iron oxide

  33. What are endospores? • Usually gram-positive bacteria • Not a reproductive structure • Survival structure for bad times • Inside PM • Form thick walls • Tolerate high heat, dehydration, poisons, radiation • Can survive up to 25 to 40 M years!!!!!!!! • Problem for food industry! • Botulism

  34. How are spores formed? • Sporogenesis • Usually resource scarcity triggers • Carbon, nitrogen, etc. • Spore is highly dehydrated • Vegetative state • Favorable conditions • Germination

  35. Prokaryotic domain

  36. What are taxonomic groups of bacteria? • Gracilicutes • Gram - • Firmicutes • Gram + • Tenricutes • (no cell cell—e.g. mycoplasmas) • Mendosicutes • (Archaebacteria)

  37. What’s the difference between a species and a strain? • Species: share similar pattern of traits • Subspecies/strain/type: same species with differing characteristics • Serotypes: unique antibody response in host

  38. What about unusual bacteria? • Rickettsias • Parasitic, gram negative • Arthropod vector • RMSF • Q Fever

  39. What about unusual bacteria? • Chlamydias • Parasitic • No vector Photo from: http://www.sexually-transmitted-diseases.info/images/std_chlamydia.jpg

  40. What about Mendosicutes? • No PPG • 70S • Extremophiles • Halophiles • Thermophiles • Methanophiles Photo from: http://people.westminstercollege.edu/faculty/tharrison/gslfood/studentpages/pinkwater2.JPG

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