Prokaryotic & eukaryotic cells 3


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Prokaryotic & eukaryotic cells 3

  1. 1. Functional Anatomy of Prokaryotic and Eukaryotic Cells
  2. 2. • Prokaryote comes from the Greek words for prenucleus• Eukaryote comes from the Greek words for true nucleus.
  3. 3. Prokaryote Eukaryote• One circular • Paired chromosome, chromosomes, not in a in nuclear membrane membrane• No histones • Histones• No organelles • Organelles• Peptidoglycan • Polysaccharide cell walls cell walls• Binary fission • Mitotic spindle
  4. 4. Prokaryote• One circular chromosome, not in a membrane• No histones• No organelles• Peptidoglycan cell walls• Binary fission
  5. 5. Eukaryote• Paired chromosomes, in nuclear membrane• Histones• Organelles• Polysaccharide cell walls• Mitotic spindle
  6. 6. Prokaryote• Average size: 0.2 -1.0 µm 2 - 8 µm• Basic shapes
  7. 7. Arrangements• Coccus – “ Berry”, round, oval
  8. 8. 2. Bacilli – Diplobacilli, Streptobacilli, Coccobacilli
  9. 9. 3. Spirals / Spirochetes – have 1 or more twist
  10. 10. Structures External to the Cell wall• 1. Glycocalyx• 2. Flagella• 3. Axial Filaments• 4. Fimbria• 5 Pilus
  11. 11. Glycocalyx• Outside the cell wall• Usually sticky2 types: 1. Capsule - neatly organized 2. Slime Layer - unorganized & loose• Extracellular polysaccharide allows cell to attach• Capsules prevent phagocytosis ( Virulence Factor)•
  12. 12. Flagella• Outside cell wall, for Locomotion• Made of chains of flagellin• Attached to a protein hook
  13. 13. Axial Filaments• Endoflagella, For Locomotion• In spirochetes ( Treponema pallidum)• Anchored at one end of a cell• Rotation causes cell to move
  14. 14. Fimbria & Pilus• Fimbriae - allow attachment (Neisseria gonorrhea) - hairlike, short• Pili - used to transfer DNA from one cell to another ( Sex pili)
  15. 15. Cell Wall• Complex, Semi-rigid structure 1. Protects the interior of the cell (prevents osmotic lysis) 2. Maintains the shape 3. Point of anchorage of FlagellaMade of peptidoglycan (in bacteria), Virulence Factor
  16. 16. Peptidoglycan - Polymer of disaccharide N-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM) - Linked by polypeptides
  17. 17. Gram-Positive cell walls• Thick peptidoglycan• Teichoic acids• In acid-fast cells, contains mycolic acid• May regulate movement of cations• Polysaccharides provide antigenic variation
  18. 18. Gram-Negative Outer Membrane• Thin peptidoglycan• No teichoic acids• Outer membrane• Lipopolysaccharides, lipoproteins, phospholipids• Protection from phagocytes, complement, antibiotics
  19. 19. Gram Stain MechanismCrystal violet-iodine crystals form in cellGram-positive - Alcohol dehydrates peptidoglycan - CV-I crystals do not leaveGram-negative - Alcohol dissolves outer membrane and leaves holes in peptidoglycan - CV-I washes out
  20. 20. Structures Internal to the Cell Wall• 1. Plasma Membrane• 2. Cytoplasm• 3. Nuclear area• 4. Ribosomes• 5. Inclusion bodies• 6. Endospores
  21. 21. Plasma Membrane / Cytoplasmic Membrane
  22. 22. • Phospholipid bilayer• Peripheral proteins• Integral proteins• Transmembrane proteins
  23. 23. • Selective permeability allows passage of some molecules Large molecules – inhibited Small molecules – allowed to pass - H+, O, Lipid soluble• Damage to the membrane by alcohols, quaternary ammonium (detergents) and polymyxin antibiotics causes leakage of cell contents.
  24. 24. Movement Across Membranes• Simple diffusion – Movement of a solute from an area of high concentration to an area of low concentration.• Facilitative diffusion - Solute combines with a transporter protein in the membrane.
  25. 25. • Osmosis Movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower waterOsmotic pressure The pressure needed to stop the movement of water across the membrane.
  26. 26. Cytoplasm• Cytoplasm is the substance inside the plasma membrane - 80% water, proteins, CHON, Lipids inorganic ions - where the nuclear area, ribosomes & ribosomes are found.
  27. 27. Nuclear Area• Stores the bacterial genetic information.• No nuclear envelope• Attached to plasma membrane• Bacterial Chromosomes - single, long, continuously arranged double stranded DNA.• Plasmid - small, circular double stranded DNA separate from chromosomal DNA capable of replicating
  28. 28. • Function of Plasmids: 1. Genes for antibiotic resistance 2. Tolerance to toxic metals 3. Production of toxins 4. Synthesis of enzymes
  29. 29. Ribosomes• Circular, Site of protein synthesis• Site for antibiotic attachment
  30. 30. Inclusions• Metachromatic granules• Polysaccharide granules• Lipid inclusions• Sulfur granules• Magnetosomes
  31. 31. Endospores• Resting cells, formed when essential nutrients are depleted• Resistant to desiccation, heat, chemicals• Bacillus, Clostridium• Sporulation: Endospore formation• Germination: Return to vegetative state
  32. 32. Eukaryotic Cells
  33. 33. Flagella and Cilia
  34. 34. Cell Wall• Cell wall Plants, algae, fungi Carbohydrates• Cellulose, chitin, glucan, mannan• Glycocalyx Carbohydrates extending from animal plasma membrane Bonded to proteins and lipids in membrane No Peptidoglycan
  35. 35. Plasma Membrane• Phospholipid bilayer• Peripheral proteins• Integral proteins• Transmembrane proteins• Sterols• Glycocalyx carbohydrates• Selective permeability allows passage of some molecules• Simple diffusion• Facilitative diffusion• Osmosis• Active transport
  36. 36. • Endocytosis• Phagocytosis: Pseudopods extend and engulf particles• Pinocytosis: Membrane folds inward bringing in fluid and dissolved substances
  37. 37. Organelles• Membrane-bound:• Nucleus Contains chromosomes• ER Transport network• Golgi complex Membrane formation and secretion• Lysosome Digestive enzymes• Vacuole Brings food into cells/stores• Mitochondrion Cellular respiration• Chloroplast Photosynthesis• Peroxisome Oxidation of fatty acids; destroys H2O2
  38. 38. Nucleus
  39. 39. Endoplasmic Reticulum
  40. 40. Golgi Complex
  41. 41. Lysosomes
  42. 42. Mitochondrion
  43. 43. Chloroplast