MICB Quiz #1 - Lab procedures, Exercises 1 and 2

• binomial system: a system of naming organisms that uses the genus and species name
• pure culture: each cell is a direct descendant of a single cell from a culture containing cells of only one species
• culture medium: a liquid or solid that contains nutrients and other substances needed for the growth of microorganisms
• colony: a visible mass or population of cells originating from a single cell
• agar: complex polysaccharide, usually extracted from red algae, that is used as a solidifying agent in the preparation of a culture media. Hardens at 40-42C.
• prodigiosin: A dark red crystalline pigment, C₂₀ H₂₅ N₃ O, with antibiotic properties, which is produced by certain bacteria of the genus Serratia (family Enterobacteriaceae), especially S. marcescens, and has a molecule containing three linked pyrrole rings.
• aseptic technique: series of proper procedures used to prevent unwanted microorganisms from contaminating a specimen.
• Drop-dilution method: Represents a qualitative method, bacterial suspension is dispersed in a sterile diluent, frequently are more reliable than streak plating procedures.
• Streak plate - Serratia marcescens: deep-red color due to prodigiosin, form circular, elevation convex, entire edge
• Streak plate - Micrococcus luteus: color yellow, form punctiform, elevation raised, entire edge
• 1 microliter = 0.001 milliliters
• P20 micropipette: 0.5-20 microliters
• P200 micropipette: 20 - 200 microliters
• P1000 micropipette: 200 - 1000 microliters
• bright-field microscope: forms a dark image against a brighter background, 2 magnifying lenses (ocular and objective). Total magnifying power = objective lens x ocular lens
• objective lens: a lens that is used to focus light onto the specimen
• ocular lens: magnifies the real image formed by objective lens
• coarse and fine adjustment knobs: raise and lower the stage
• condensor: focuses a cone of light from light source onto the slide
• numerical aperture: characteristic of each lens and is a measure of light-gathering ability
• refractive index: measures the amount that light rays are bent as they pass different media (index of air is 1.0 and glass is 1.52)
• magnification: increases the apparent angle subtended at the eye by objects within the microscope field
• resolution: the degree of definition of the fine structure of an object being observed - how sharp the magnified image is. Permits the perception of two closely adjacent points as separate
• Saccharomyces cerevisiae: domain eukarya - shape coccus, grouping micrococcus
• Wet mount of Escherichia coli: color green, shape bacillus (rod), grouping chain/pair
• basal body: spans the cell envelope and consists of a rod and series of stabilizing rings. Imparts rotation, functioning like a tiny rotary motor.
• hook: extends out from basal body, curved
• filament: attached to hook and extending into environment
• general structure of a bacterial flagellum: basal body, hook, filament
• peritrichous bacterium: flagella distributed over entire surface
• monotrichous bacterium: single flagellum located at one pole of the cell
• amphitrichous bacterium: has a single flagellum at each end
• lophotrichous bacteria: cluster of flagella at one or both ends
• brownian motion: random movement of particles in a liquid or gas, caused by collisions with other particles
• Rhodospirillum rubrum: motile, shape spirillum (rigid, helical)
• Staphylococcus epidermidis: non-motile, shape coccus (spherical), grouping clusters of 2-3
• darkfield microscopy: used to view living unstained microorganisms. Has a darkfield condensor that allows light to pass through the specimen. Used to view very thin and distinctly shaped bacteria
• phase-contrast microscopy: way to view living cells and bacterial motility, specimen appears dark and well-defined
• How does oil help in viewing objective at 100x: eliminates 2 refractive surfaces, helps bring more light to objective lens and creates a clearer image
• Relationship between amount of light and magnification: as magnification increases, more light is needed