M Ashcraft Microscopy and Cell Structure o Principles of Light Magnification 2 lens objective and ocular to create a compound microscope Clearly separates objects that are close together Refraction when light passes though air Reflective index relative velocity of light as it passes through a medium Resolution Contrast reflects the number of shades in the specimen Various degrees of shades revealmost important information Staining helps see contrast o Prokaryotics vs Eukaryotic cell Prok have larger surface area to volume ratio making it easier to excrete wastes and take in materials resulting in a higher division multiplying rate Prok Are smaller and more vulnerable to predators and parasites Chemical processes are fundamentally different regardless of similar characteristics A rod shaped bacteria A rod shaped bacteria mistaken for a coccus Morphology of Prokaryotic Cells o Shapes Bacillus Coccobacillus Vibrio Spirillum Spiriochete Pleomorphic o Groupings A short curved rod Curved spiral rod Can change its shape Long Helical cell with a flexible cell wall and a unique mechanism for motility Dipliococci coccus packets of 2 gonorrhea Chains strep Binary fission adhere to one another in a the planes of which they divide Division among 2 to 3 plains form cubical packet Sarcina Division among many random planes clusters Staph Cells living in a slime layer caused by a polysaccharide produced by the cells adhering to the surface o Multicellular Associations Live in communities Biofilms More resistant to disinfectants and antibiotics When water or nutrients low the cells aggregate to form a fruiting body The Cytoplasmic Membrane o Delicate thin structure that surrounds the cytoplasm and defines cell boundaries o Structure and Chemistry Hydrophilic phospholipid heads and hydrophobic tails o Permeability Selectively permeable have receptors Simple Diffusion The greater the gradient the faster the movement Osmosis o The Role of Cytoplasmic Membrane in Energy Transformation M Ashcraft Helps the cell convert energy into a useable form Only happens in the prokaryotic eukaryotic have membranous organelles Electron transport chain series of protein complexes embedded in membrane Transfer electrons which eject protons from the cell This causes a proton gradient across the cell Positively charged concentrated outside and hydroxyl neg inside This creates the electrochemical gradient o o And powered the proton motive force stored battery Direct movement across the Cytoplasmic Membrane o Transport system mechanism involving nutrients and other molecules to enter the cell Carries out process like importing material into cell synthesize ATP Down concentration gradient with the help of carrier proteins Use transport molecules carrier proteins permeases transport proteins to cross Facilitated Diffusion passive transport Active Transport Moves compounds up the concentration gradient and powered by E Use of Proton Motive Force o Move the material into the cell along with a proton from the outside Efflux pumps used to oust antibacterial drugs use proton motive o These systems part of the major facilitator family MFS Use of ATP o ABC transport systems ATP Binding Cassette Elaborate protein binding components Binding proteins reside outside the membrane Group Translocation Process that chemically alters a molecule during its passage through the membrane o o Glucose etc are phosophorylated during transport by a phosphotransferase system o Secretion move proteins that they synthesize out of the cell General secretory pathway primary mechanism used to secrete proteins synthesized by cell Recognizes the secretory proteins by signal sequence amino acid at 1 end Cell Wall o Functions o Peptidoglycan Defines cell boundaries Protects the cell from bursting Surrounds cytoplasmic membrane Determines cell shape Causes the rigidity of cell walls Composed of alternating sub units N acetylmuramic acid NAM and N acetlyglucosamine NAG Components are covalently bonded to form a glycan chain This serves as a backbone of the peptido Molecule because of its high molecular weight Attached to each NAM molecule is 4 amino acids Cross linkages can form forming a 3 dimensional molecule Gram Staining o Hans Christian Gram Primary Stain crystal violet Mordant dilute iodine Dye iodine complex less soluble M Ashcraft Mordant means that it helps the violet stay inside of the cell Decolorizer alcohol Countertain safrinin Removes primary dye from Gram cells Colors cells that lost crystal stain o The Gram positive Cell Wall Thick layer of peptido Teichoic acids chains of a common subunit either ribitol phosphate or glycerol phosphate to which various sugars are attached gives neg surface charge Usually attached to peptido molecule through the covalent NAG Some are attached to the membrane lipoteichoic Staining GRAM NEG OR POSITIVE BACTERIAL STAIN Mordant iodine complex less soluble Primary stain crystal violet Decolorizer alcohol removes primary stain from gram neg Counterstain safrin colors cells that lost color o The Gram negative Cell Wall Thin layer of peptido Outside the membrane is a outer membrane that is embedded with proteins Has a outer membrane and an inner cytopasmic membrane The Outer Membrane Serves as a barrier for most molecules Small molecules and ions pass through the membrane via porins channel proteins spanning the membrane The outside is made up of lipopolysaccharides LPS layer not phosopholipids o o Some parts medically significant Lipid A Helps the body recognize invading bacteria small amounts Causes the symptoms related to endotoxin Anchors LPS in the bilipid layer In large amounts can cause an immune response that can be toxic and damaging toxic shock o O specific polysaccharide Portion of LPS that is directed away from the membrane at the opposite end of lipid A Used to ID stains Periplasm The gell like material in the region between the cytoplasmic membrane and the outer membrane All secreted proteins exist here unless transported out of the cell o Thus involved in many cellular activities like ABC transport o Antibactieral Substances that Target Peptidogyclan Pencillin beta lactam antibiotics Interfere with pepido synthesis Far more effective against Gram pos than Gram neg o More difficult to penetrate outer membrance of Gram neg Lysozyme Found in many body fluids like tears and saliva Breaks the bonds between the NAG and NAM molecules digests PG selective toxicity o o kill the bacteria without damaging the