Microbiology & Immunology PDF

Introduction to Bacteriology © 2013 Pearson Education, Inc.  Prokaryotic and Eukaryotic Cells pre A Prokaryote comes from the Greek words for prenucleus. not or Eukaryote comes from the Greek words for 6- true nucleus....

Introduction to Bacteriology © 2013 Pearson Education, Inc.  Prokaryotic and Eukaryotic Cells pre A Prokaryote comes from the Greek words for prenucleus. not or Eukaryote comes from the Greek words for 6- true nucleus. © 2013 Pearson Education, Inc.  Prokaryote Eukaryote no ends can't be One circular chewed > - so Paired chromosomes, chromosome, not in a in nuclear membrane membrane Histones No histones Golgi ER membranebound , , mitochondria lysosomes No organelles Organelles Perioxosomes Loading… , Bacteria: peptidoglycan Polysaccharide cell cell walls protein-sugar walls Archaea: pseudomurein Mitotic spindle cell walls Binary fission © 2013 Pearson Education, Inc.  Prokaryotic Cells: Shapes 2 micro 2-8 · - Average size: 0.2–1.0 µm 2–8 µm Most bacteria are monomorphic (single shape) A few are pleomorphic (few shapes Monomorphic Pleomorphic © 2013 Pearson Education, Inc.  Basic Shapes round Coccus (spherical) Bacillus (rod-shaped) Loading… © 2013 Pearson Education, Inc.  Basic Shapes Spiral Vibrio (bent-like) Spirillum Idense mass) , Spirochete (thinner mass © 2013 Pearson Education, Inc.  Special Shapes Star Carchaian bacterial Stella sp. Rectangular (square-like) Haloarcula sp. sea © 2013 Pearson Education, Inc.  Arrangements spiral form can't arrangements Pairs: diplococci, diplobacilli Clusters: staphylococci me grapes Chains: streptococci, streptobacilli © 2013 Pearson Education, Inc. Figure 4.6 The Structure of a Prokaryotic Cell. The drawing below and the Cell micrograph at right show a bacterium Capsul wall sectioned lengthwise to reveal the e Although the nucleoid appears Pilu internal composition. Not all bacteria split in the photomicrograph, s have all the structures shown; only the thinness of the “slice” does structures labeled in red are found in not convey theobject’s depth. all bacteria. Cytoplas m 70S Ribosomes Plasma membrane Nucleoid containing DNA Inclusion s Plasmi d Fimbria e Capsul e Cell wall Plasma membran e Flagell a © 2013 Pearson Education, Inc..  Glycocalyx not every bacteria has glycocalyx Outside cell wall Usually sticky made dense holight both 1) Capsule: neatly organized polysach. 2) Slime layer: unorganized and loose may extend sticky - Extracellular polysaccharide allows cell to attach Capsules prevent phagocytosis hide from system immune Ex : teeth on morning © 2013 Pearson Education, Inc.  Flagella anchored to all wall Outside cell wall protein Made of chains of flagellin Attached to a protein hook connects flagella anchor to Anchored to the wall and membrane by the Loading… basal body (different based on cell wall type) push or pro pel to cell move © 2013 Pearson Education, Inc. Figure 4.7 Arrangements of bacterial flagella. Peritrichous Monotrichous and polar Lophotrichous and polar Amphitrichous and polar © 2013 Pearson Education, Inc.  Motile Cells Ir like prope & Rotate flagella to run or tumble (turn) Move toward or away from stimuli (taxis) Flagella proteins are H antigens (e.g., E. coli O157:H7) http://www.youtube.com/w atch?v=891M1TH99_8 © 2013 Pearson Education, Inc.  Axial Filaments monotrichous comes out one end a wraps itself around the entire Also called endoflagella length of bacteria In spirochetes corkscrew Anchored at one end of a cell Rotation causes cell to move http://www.youtube.com/watch? v=O0y7X5acK8M http://www.youtube.com/watch? v=RUV6mr7MVBI © 2013 Pearson Education, Inc.  Fimbriae and Pili Fimbriae allow attachment © 2013 Pearson Education, Inc.  Fimbriae and Pili can extend out a interact o others to break Pillis down Pili ↳ conjugation Facilitate transfer of DNA from one cell to another (Sex Pilis) Gliding motility Twitching motility http://www.youtube.com/watch?v=USZdKL6I7H8 © 2013 Pearson Education, Inc.  The Cell Wall most bacteria has all wall Prevents osmotic lysis water can't so come in Made of peptidoglycan (in bacteria) Polymer of disaccharide: is ver repeating peptideshol N-acetylglucosamine (NAG) N-acetylmuramic acid (NAM) © 2013 Pearson Education, Inc.  Peptidoglycan in Gram-Positive Bacteria Linked by polypeptides Peptide cross bridges Tetrapeptide © 2013 Pearson Education, Inc.  Gram-Positive Cell Walls Teichoic acids Lipoteichoic acid links to plasma membrane Wall teichoic acid links to peptidoglycan May regulate movement of cations because - charge © 2013 Pearson Education, Inc.  Gram-Negative Outer Membrane Outer membrane is made up of Lipopolysaccharides, lipoproteins, phospholipids The periplasm forms between the outer membrane and the plasma membrane © 2013 Pearson Education, Inc.  Gram-Negative Outer Membrane Protection from phagocytes and antibiotics O polysaccharide antigen, e.g., E. coli O157:H7 Lipid A is an endotoxin Porins (proteins) form channels through membrane © 2013 Pearson Education, Inc.  Gram-Positive Gram-Negative Cell Wall Cell Wall Thick peptidoglycan Thin peptidoglycan Teichoic acids Outer membrane Periplasmic space © 2013 Pearson Education, Inc.  The Gram Stain Mechanism Crystal violet-iodine crystals form in cell attach in walls Gram-positive Alcohol dehydrates peptidoglycan CV-I crystals do not leave during decolorizing traps Gram-negative Alcohol dissolves outer membrane and leaves holes in peptidoglycan CV-I washes out during decolorizing © 2013 Pearson Education, Inc. Table 4.1 Some Comparative Characteristics of Gram-Positive and Gram-Negative Bacteria © 2013 Pearson Education, Inc.  Atypical Cell Walls Acid-fast cell walls Gram-positive like cell walls Waxy lipid (mycolic acid) bound to peptidoglycan Mycobacterium ↓b instead · echoic acid © 2013 Pearson Education, Inc.  Atypical Cell Walls Mycoplasmas Lack cell walls Sterols in plasma membrane Archaea Wall-less, or Walls of pseudomurein (lack NAM and D-amino acids) © 2013 Pearson Education, Inc.  Damage to the Cell Wall Lysozyme digests disaccharide in peptidoglycan Penicillin inhibits peptide bridges in peptidoglycan (Ab) NAC © 2013 Pearson Education, Inc.  The Plasma Membrane Phospholipid bilayer associateda membrane Peripheral proteins Stuck in membrane Integral proteins across membrane Transmembrane proteins © 2013 Pearson Education, Inc.  The Plasma Membrane Selective permeability allows passage of some molecules gases O2 CO2 not charged , , Enzymes for ATP production found in plasia membrane Photosynthetic pigments on foldings called chromatophores Loading… © 2013 Pearson Education, Inc.  The Plasma Membrane Damage to the membrane by alcohols, detergents, and polymyxin antibiotics causes leakage of cell B contents © 2013 Pearson Education, Inc.  Cytoplasm liquide cytosol jelly like The substance inside the plasma membrane © 2013 Pearson Education, Inc.  The Nucleoid Bacterial chromosome ↑ conc. Of enzymes - transcription translation © 2013 Pearson Education, Inc.  The Prokaryotic Ribosome Protein synthesis 70S ↳ 50S + 30S subunits Eukaryotic is 80s © 2013 Pearson Education, Inc.  Inclusions something that cell stores Metachromatic granules (volutin)—phosphate reserves Polysaccharide granules—energy reserves Lipid inclusions—energy reserves Sulfur granules—energy reserves H peroxide + Magnetosomes—iron oxide (destroys H2O2) rust © 2013 Pearson Education, Inc.  Endospores seeds Resting cells Istate Resistant to desiccation, heat, chemicals Bacillus, Clostridium produces Sporulation: endospore formation Germination: return to vegetative state © 2013 Pearson Education, Inc. Figure 4.21a Formation of endospores by sporulation. Cell Cytoplasm Spore septum begins to isolate wall newly replicated DNA and a Plasma membrane starts to small portion of cytoplasm. surround DNA, cytoplasm, and membrane isolated in step 1. Plasma membrane Bacterial chromosome (DNA) Sporulation, the process of endospore formation Spore septum surrounds isolated portion, forming forespore. Two membranes Peptidoglycan layer forms between membranes. Spore coat forms. Endospore is freed from cell. © 2013 Pearson Education, Inc.  Microscopy © 2013 Pearson Education, Inc. Figure 3.2 Microscopes and Magnification. Unaided eye ≥ 200 m increases Light microscope resolution 200 nm – 10 mm Tick Scanning Actual size electron microscope 10 nm – 1 mm Red blood cells Transmission electron microscope E. coli bacteria 10 pm – 100 m T-even bacteriophages (viruses) Atomic force microscope 0.1 nm – 10nm DNA double helix © 2013 Pearson Education, Inc.  Microscopy: The Instruments A simple microscope has only one lens © 2013 Pearson Education, Inc.  Light Microscopy The use of any kind of microscope that uses visible light to observe specimens Types of light microscopy Compound light microscopy Darkfield microscopy Phase-contrast microscopy Differential interference contrast microscopy Fluorescence microscopy Confocal microscopy © 2013 Pearson Education, Inc. Figure 3.1a The compound light microscope. Ocular lens (eyepiece) Remagnifies the Fine focusing knob image formed by the objective lens Coarse focusing knob Body tube Transmits the image from the objective lens to the ocular lens Arm Objective lenses Primary lenses that magnify the specimen Stage Holds the microscope slide in position Condenser Focuses light through specimen Diaphragm Controls the amount of light entering the condenser Principal parts and Illuminator Light source functions Base © 2013 Pearson Education, Inc.  Compound Light Microscopy In a compound microscope, the image from the objective lens is magnified again by the ocular lens Total magnification = objective lens X ocular lens 10 X 10 = 100 © 2013 Pearson Education, Inc.  Compound Light Microscopy Resolution is the ability of the lenses to distinguish two points separate things 0 I mm. A microscope with a resolving power of 0.4 nm can distinguish between two points ≥ 0.4 nm © 2013 Pearson Education, Inc.  Compound Light Microscopy The refractive index is a measure of the light-bending ability of a medium The light may bend in air so much that it misses the small high-magnification lens Immersion oil is used to keep light from bending without it , it bends © 2013 Pearson Education, Inc.  Brightfield Illumination light pass through object , object block some of light, shows up as dark Dark objects are visible against a bright background Light reflected off the specimen does not enter the objective lens © 2013 Pearson Education, Inc.  Darkfield Illumination light that passes through looking dark , any light absorbed by specimen looks light Light objects are visible against a dark background Light reflected off the specimen enters the objective lens © 2013 Pearson Education, Inc.  Phase-Contrast Microscopy Accentuates diffraction of the light that passes through a specimen changes a phases of light passing through object © 2013 Pearson Education, Inc.  Differential Interference Contrast Microscopy Accentuates diffraction of the light that passes through a specimen; uses two beams of light © 2013 Pearson Education, Inc.  Fluorescence Microscopy Uses UV light Fluorescent substances absorb UV light and emit visible light Cells may be stained with fluorescent dyes (fluorochromes) © 2013 Pearson Education, Inc.  Confocal Microscopy Cells are stained with fluorochrome dyes Short-wavelength (blue) light is used to excite the dyes The light illuminates each plane in a specimen to produce a three-dimensional image Up to 100 µm deep © 2013 Pearson Education, Inc.  Other microscopy methods that do not use light Scanning Acoustic Microscopy Electron Microscopy TEM SEM Scanning Probe Microscopy Atomic Force © 2013 Pearson Education, Inc. Scanning Acoustic Microscopy (SAM) Measures sound waves that are reflected back from an object Used to study cells attached to a surface Resolution 1 µm © 2013 Pearson Education, Inc.  Electron Microscopy Uses electrons instead of light The shorter wavelength of electrons gives greater resolution © 2013 Pearson Education, Inc. Transmission Electron Microscopy (TEM) Ultrathin sections of specimens Electrons pass through specimen, then electromagnetic lenses, to a screen or film Specimens may be stained with heavy-metal salts © 2013 Pearson Education, Inc.  Transmission Electron Microscopy (TEM) 10,000–100,000 ; resolution 2.5 nm © 2013 Pearson Education, Inc. Scanning Electron Microscopy (SEM) An electron gun produces a beam of electrons that scans the surface of a whole specimen Secondary electrons emitted from the specimen produce the image © 2013 Pearson Education, Inc.  Scanning Electron Microscopy (SEM) 1,000–10,000 ; resolution 20 nm © 2013 Pearson Education, Inc.  Scanned-Probe Microscopy Atomic force microscopy (AFM) uses a metal-and-diamond probe inserted into the specimen Produces three-dimensional images © 2013 Pearson Education, Inc.  Preparing Smears for Staining to secrobesa small Staining: coloring the microbe with a dye that emphasizes certain structures Smear: a thin film of a solution of microbes on a slide single layer of cells A smear is usually fixed to attach the microbes to the slide and to kill the microbes © 2013 Pearson Education, Inc.  Preparing Smears for Staining Live or unstained cells have little contrast with the surrounding medium. Researchers do make discoveries about cell behavior by observing live specimens. © 2013 Pearson Education, Inc.  Preparing Smears for Staining most bacteria cells are 71 charged Stains consist used of a positive and negative ion a most In a basic dye, the chromophore is a cation ( ) + In an acidic dye, the chromophore is an anion ) 1 - Staining the background instead of the cell is called negative staining - © 2013 Pearson Education, Inc.  Simple Stains can get : of bacteria - shape some flagella-arrangement - Simple stain: use of a single basic dye A mordant may be used to hold the stain or coat the stick better specimen to enlarge it to © 2013 Pearson Education, Inc.  Differential Stains diagnostic purposes Used to distinguish between bacteria Gram stain " Acid-fast stain © 2013 Pearson Education, Inc.  Gram Stain > cell - wall Classifies bacteria into gram-positive or gram-negative of peptico- Gram-positive bacteria have thick cell walls glycan layers acid , technic Gram-negative bacteria have thin cell walls membranes 2 1) add 2) add interact with crystal violet dehydrate a 3) add pep : destroye & 4) add © 2013 Pearson Education, Inc.  Acid-Fast Stain - identify cell wall w mycolic acid Stained waxy cell wall is not decolorized by acid-alcohol Mycobacterium leprosi mycobactrim 1) red 2) 3) © 2013 Pearson Education, Inc.  Special Stains structures Used to distinguish parts of cells Capsule stain Endospore stain Flagella stain © 2013 Pearson Education, Inc.  Negative Staining for Capsules Cells stained and capsules are not Type of Negative stain the cellsa background but not capsules © 2013 Pearson Education, Inc.  Endospore Staining Primary stain: malachite green, usually with heat (needed for stain penetration) Decolorize cells: water Counterstain: safranin © 2013 Pearson Education, Inc.  Flagella Staining Mordant on flagella Carbolfuchsin simple stain red a mordant © 2013 Pearson Education, Inc.