M. AshcraftMicroscopy and Cell Structureo Principles of Light Magnification- 2 lens objective and ocular to create a compound microscope Resolution- 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 Contrast: reflects the number of shades in the specimen- Various degrees of shades revealmost important information- Staining helps see contrasto 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 Morphology of Prokaryotic Cells o Shapes Bacillus- A rod shaped bacteria Coccobacillus- A rod shaped bacteria mistaken for a coccus Vibrio- A short, curved rod Spirillum- Curved, spiral rod Spiriochete- Long. Helical cell with a flexible cell wall and a unique mechanism for motility Pleomorphic- Can change its shapeo Groupings Binary fissionadhere to one another in a the planes of which they divide- Dipliococcicoccus, packets of 2 (gonorrhea) - Chainsstrep Division among 2 to 3 plains form cubical packet (Sarcina) Division among many random planes clusters (Staph)o Multicellular Associations  Live in communities Biofilms- Cells living in a slime layer caused by a polysaccharide produced by the cells adhering to the surface- More resistant to disinfectants andantibiotics  When water or nutrients low, the cellsaggregate to form a fruiting body The Cytoplasmic Membraneo Delicate, thin structure that surrounds thecytoplasm and defines cell boundarieso Structure and Chemistry Hydrophilic phospholipid heads andhydrophobic tails o Permeability  Selectively permeable, have receptors Simple Diffusion- The greater the gradient, the faster themovement - Osmosiso The Role of Cytoplasmic Membrane in EnergyTransformationM. 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) insideo This creates the electrochemical gradiento And powered the proton motive force  “stored battery” Carries out process like importing material into cell & synthesize ATPDirect movement across the Cytoplasmic Membraneo Transport system: mechanism involving nutrients and other molecules to enter the cell Use transport molecules (carrier proteins, permeases, transport proteins) to cross Facilitated Diffusion (passive transport)- Down concentration gradient with the help of carrier proteins Active Transport- Moves compounds up the concentration gradient and powered by E- Use of Proton Motive Forceo Move the material into the cell along with a proton from the outsideo Efflux pumps: used to oust antibacterial drugs, use proton motive These systems part of the major facilitator family (MFS)- Use of ATPo ABC transport systems: ATP Binding Cassette  Elaborate protein binding components Binding proteins: reside outside the membrane- Group Translocationo Process that chemically alters a molecule during its passage through the membraneo Glucose, etc are phosophorylated during transport by a phosphotransferase systemo 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 endCell Wall o Functions Defines cell boundaries Protects the cell from bursting  Surrounds cytoplasmic membrane Determines cell shapeo Peptidoglycan  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 aglycan chain- This serves as a backbone of thepeptido. Molecule because of its highmolecular weight- Attached to each NAM molecule is 4amino acids- Cross linkages can form, forming a 3dimensional molecule Gram Stainingo Hans Christian Gram  Primary Stain crystal violet Mordant dilute iodine- Dye, iodine complex, lesssolubleM. Ashcraft- Mordant means that it helps the violet stay inside of the cell Decolorizer - alcohol- Removes primary dye from Gram cells Countertain – safrinin- 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 sugarsare attached (gives neg surface charge)- Usually attached to peptido molecule, through thecovalent NAG- Some are attached to the membrane: lipoteichoic  Staining (GRAM NEG OR POSITIVE BACTERIAL STAIN)- Primary stain: crystal violet- Mordant: iodine complexless soluble - Decolorizer: alcohol removes primary stain fromgram neg- Counterstain: safrin colors cells that lost coloro The Gram negative Cell Wall Thin layer of peptido Outside the membrane is a outer membrane that isembedded with proteins  Has a outer membrane and an inner cytopasmicmembrane The Outer Membrane - Serves as a barrier for most molecules - Small molecules and ions pass through themembrane via porins, channel proteins spanning themembrane- The outside is made up of lipopolysaccharides (LPSlayer) not phosopholipidso Some parts medically significanto Lipid A Anchors LPS in the bilipid layer Helps the body recognize invading bacteria (small amounts) Causes the symptoms related to endotoxin- In large amounts can cause an immune response that can be toxic and damagingtoxic shocko 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 cello Thus, involved in many cellular activities, like ABC transport o Antibactieral Substances that Target Peptidogyclan  Pencillin (beta-lactam antibiotics) -