Flagella• Outside cell wall, for Locomotion• Made of chains of flagellin• Attached to a protein hook
Axial Filaments• Endoflagella, For Locomotion• In spirochetes ( Treponema pallidum)• Anchored at one end of a cell• Rotation causes cell to move
Fimbria & Pilus• Fimbriae - allow attachment (Neisseria gonorrhea) - hairlike, short• Pili - used to transfer DNA from one cell to another ( Sex pili)
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
Peptidoglycan - Polymer of disaccharide N-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM) - Linked by polypeptides
Gram-Positive cell walls• Thick peptidoglycan• Teichoic acids• In acid-fast cells, contains mycolic acid• May regulate movement of cations• Polysaccharides provide antigenic variation
Gram-Negative Outer Membrane• Thin peptidoglycan• No teichoic acids• Outer membrane• Lipopolysaccharides, lipoproteins, phospholipids• Protection from phagocytes, complement, antibiotics
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
• Phospholipid bilayer• Peripheral proteins• Integral proteins• Transmembrane proteins
• 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.
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.
• 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.
Cytoplasm• Cytoplasm is the substance inside the plasma membrane - 80% water, proteins, CHON, Lipids inorganic ions - where the nuclear area, ribosomes & ribosomes are found.
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
• Function of Plasmids: 1. Genes for antibiotic resistance 2. Tolerance to toxic metals 3. Production of toxins 4. Synthesis of enzymes
Ribosomes• Circular, Site of protein synthesis• Site for antibiotic attachment
Endospores• Resting cells, formed when essential nutrients are depleted• Resistant to desiccation, heat, chemicals• Bacillus, Clostridium• Sporulation: Endospore formation• Germination: Return to vegetative state