Presentation on theme: "Chapter 4 Prokaryotic Cell"— Presentation transcript:
1 Chapter 4 Prokaryotic Cell Functional Anatomy of Prokaryotic and Eukaryotic CellsBio 205
2 Prokaryotic Cells Comparing Prokaryotic and Eukaryotic Cells Prokaryote comes from the Greek words for prenucleus.Eukaryote comes from the Greek words for true nucleus.
3 Prokaryote Eukaryote Paired chromosomes, in nuclear membrane One circular chromosome, not in a membraneNo histonesNo organellesPeptidoglycan cell wallsBinary fissionPaired chromosomes, in nuclear membraneHistonesOrganellesPolysaccharide cell wallsMitotic spindle
7 Glycocalyx Outside cell wall Usually sticky A capsule is neatly organizedA slime layer is unorganized & looseExtracellular polysaccharide allows cell to attachCapsules prevent phagocytosisFigure 4.6a, b
8 Flagella Outside cell wall Made of chains of flagellin Attached to a protein hookAnchored to the wall and membrane by the basal bodyFigure 4.8
18 Gram-Positive cell walls Teichoic acids:Lipoteichoic acid links to plasma membraneWall teichoic acid links to peptidoglycanMay regulate movement of cationsPolysaccharides provide antigenic variationFigure 4.13b
19 Gram-Negative Outer Membrane Lipopolysaccharides, lipoproteins, phospholipids.Forms the periplasm between the outer membrane and the plasma membrane.Protection from phagocytes, complement, antibiotics.O polysaccharide antigen, e.g., E. coli O157:H7.Lipid A is an endotoxin.Porins form channels through membrane
20 Gram Stain Mechanism Crystal violet-iodine crystals form in cell Gram-positiveAlcohol dehydrates peptidoglycanCV-I crystals do not leaveGram-negativeAlcohol dissolves outer membrane and leaves holes in peptidoglycanCV-I washes out
21 Atypical Cell Walls Mycoplasmas Lack cell walls Sterols in plasma membraneArchaeaWall-less, orWalls of pseudomurein (lack NAM and D amino acids)
22 Damage to Cell Walls Lysozyme digests disaccharide in peptidoglycan. Penicillin inhibits peptide bridges in peptidoglycan.Protoplast is a wall-less cell Gram-positive cell.Spheroplast is a wall-less Gram-negative cell.L forms are wall-less cells that swell into irregular shapes.Protoplasts and spheroplasts are susceptible to osmotic lysis.