1 / 50

Chapter 4

Chapter 4. Functional Anatomy of Prokaryotic and Eukaryotic Cells. Prokaryotes can be grouped based on size, morphology and cell arrangement Morphology is genetically determined Monomorphic vs pleomorphic Size Range 0.2 to 80 um in diameter 2 to 600 um in length

oni
Download Presentation

Chapter 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 4 Functional Anatomy of Prokaryotic and Eukaryotic Cells

  2. Prokaryotes can be grouped based on size, morphology and cell arrangement • Morphology is genetically determined • Monomorphic vs pleomorphic • Size Range • 0.2 to 80 um in diameter • 2 to 600 um in length • Average size: 0.2 -1.0 µm × 2 - 8 µm

  3. Size in the Microbial World

  4. Morphology of Prokaryotic Cells • Prokaryotes exhibit a variety of shapes • Most common

  5. Spiral

  6. Uncommon Shapes Stella Haloarcula

  7. Cells may form groupings • Cells adhere together after division • Form characteristic arrangements • Depends on plan of division

  8. Neisseria • Enterococcus Micrococcus Sarcina Staphylococcus aureus

  9. Bacillus anthracis • Bacillus megaterium • Bordetella pertussis

  10. Layers External to Cell Wall • Glycocalyx • Made inside the cell; excreted to surface • General functions • Protection • Attachment • Motility

  11. Arrangements of Glycocalyx • Capsule or Slime Layer • Chemical composition varies depending on species

  12. Flagella • Filamentous appendages composed of flagellin • H antigens • Rotate powered by PMF or ATP • Taxis • Runs and tumbles

  13. Flagella structure has three basic parts • Filament • Hook • Basal body

  14. Polar - Monotrichous Polar -Lophotrichous Peritrichous Polar -amphitrichous

  15. Axial filaments • Bundles of endoflagella that spiral around cell • Spirochetes only • Corkscrew motion

  16. Fimbriae & Pili • Filaments of pilin protein • Fimbriae • Attachment • Hami – archaea only • Pili • Exchange of DNA

  17. Prokaryotic Cell Wall • Rigid structure • Determines shape of cell • Protects from osmotic pressure • Anchor point for flagella • Contributes to pathogeneses

  18. Unique chemical structure • Bacteria vs. Archaea • Gram positive vs. Gram-negative • Peptidoglycan (PTG) (murein) • Sugar found only in bacteria • Archaea may have proteins or alternate sugars • Many antimicrobials interfere with PTG synthesis • Penicillin

  19. Basic structure of PTG • Disaccharide polymer • N-acetylglucosamin (NAG) • N-acetylmuramic acid (NAM) • Glycan chain held together by amino acids • Tetrapeptide chain • Protein crossbridges may or may not be present • Mostly G+

  20. Gram positive cell wall • Thick layer of PTG • Teichoic acids • Lipoteichoic or Wall teichoic acids • Polyalcohols that provide antigenic specificity • May have external protein or sugar layer

  21. Gram-negative cell wall • Little or no PTG • Outer lipopolysaccharide membrane (LPS) • O-specific polysaccharide side chain • Lipid A endotoxin • Porin channels • Periplasm

  22. GRAM STAINING • Gram-positive and gram-negative bacteria can be identified using a “gram stain”

  23. Summary of Gram + vs. Gram – • G+ cell • many rigid layers of peptidoglycan • teichoic acids • No outer LPS membrane • 2 ring basal body anchoring flagella • G- cell • Little or no peptidoglycan • no teichoic acids • LPS outer membrane • 4 ring basal body anchoring flagella

  24. Atypical cell wall • Acid-fast cell walls • Classified as gram-positive • mycolic acid bound to PTG • Mycobacterium • Nocardia

  25. Chlamydia • Classified as Gram – with no PTG • cysteine-rich proteins

  26. No cell wall • Mycoplasmas • Sterols in plasma membrane

  27. Structures Internal to Cell Wall • Cytoplasmic membrane • Delicate thin fluid structure • Defines boundary • Serves as a semi permeable barrier

  28. Fluid mosaic model • Phospholipid Bilayer • Amphipathic

  29. Embedded with numerous proteins • receptors , transport, enzymes • Prokaryotes do not have membrane sterols • Bacteria may have hopanoids

  30. Photosynthetic pigments on in-foldings • chromatophores or thylakoids

  31. Archaea have distinct membrane lipids • Ether linkage • Diether or tetraether • Glycerol group enantiomer • Branched isoprenoid sidechain • May form mono-layer with greater rigidity

  32. Top: archaeal phospholipid, 1 isoprene sidechain, 2 ether linkage, 3 L-glycerol, 4 phosphate group Middle:bacterial and eukaryotic phospholipid: 5 fatty acid, 6 ester linkage, 7 D-glycerol, 8 phosphate group Bottom: 9 lipid bilayer of bacteria and eukaryotes, 10 lipid monolayer of some archaea.

  33. Membrane is selectively permeable • Few molecules pass through freely • Movement involves both active and passive processes

  34. passive processes • no energy (ATP) required • Along gradient • simple diffusion, facilitated diffusion, osmosis

  35. Simple diffusion • Facilitated diffusion

  36. Osmosis • Osmotic pressure

  37. active processes • energy (ATP) required • Active transport

  38. Group translocation • Phosphotransferase system • PEP group translocation PEP transferase animation

  39. Internal Structures • Structures essential for life • Chromosome • Ribosome • Optional but may provide selective advantage • Cytoskeleton • Plasmid • Storage granules • Endospores

  40. Internal Structures • Primary Chromosome • Resides in nucleoid • Typically single circular chromosome • Archaea have histone proteins but bacteria have condensinprotiens • Asexual reproduction • Binary fission, budding, fragmenting, spores

  41. Plasmids • Small DNA molecules • replicated independently • nonessential information • used in genetic engineering biotechnology

  42. Ribosomes (70S) • Composed of large and small subunits • made of riboprotein and ribosomal RNA • differ in density from eukaryotic ribosomes • target for antimicrobials

  43. Inclusions • Metachromatic granules • Polysaccharide granules • lipid inclusions • sulfur granules • carboxyzomes • magnetosomes • Gas vesicles

  44. Endospores • “Resting cells” • Highly resistant • Heat, desiccation, chemicals and UV light • Not reproduction! Endospore producers include Clostridium and Bacillus

More Related