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Micro Exam 10/5

1st Micro Exam

What are Koch's Postulates? 1. Must be present in every case of the disease, but not in healthy individuals 2. Must be isolated and grown in a pure culture 3.The same disease must result when healthy individual is inoculated with organism 4. Must isolate from inoculated individua
Why can't we use all of Koch's postulates today? Some organisms cannot be grown in a pure culture, inoculating a healthy human is unethical, may be replaced by genetic and molecular evidence, some individuals may be naturally immune to the disease
What produces an image in dark field microscopy? Only the light refracted by the object.
What is dark field good for? Internal structure in live, unstained cells
What does phase contrast do? Changes differences in refractive indexes into variations of light intensity
What does differential interference contrast microscopy do? Uses 2 beams of plane polarized light to form a colored, 3D image
Transmission EM uses electrons that pass through an organism to form an image: shape and fine details of organelles
Scanning EM Forms image from electrons released from organism’s surface: 3D detailed image
Confocal Focuses light from all areas of the object, not just the plane of focus
Scanning Probe Move a sharp probe over the electron cloud, apply a small voltage between the two, this current is sensitive to distance
What are the 3 parts of a lipopolysaccharide? 1. Lipid A 2. Core polysaccharide 3. O side chain
Where is an LPS located? Embedded in the outer membrane
What charge does LPS give to the cell surface, what does this do? Negative, help attach to surfaces and form biofilm
What does LPS contribute to the cell? Stability, permeability barrier, protection, can act as an endo toxin
What substance forms capsules and slime layers? Glycocalyx
Diplococci pairs
Streptococci Chains
Staphylococci grape-like clusters
Tetrads 4 cocci in a square
Sarcinae cubic configuration of 8 cocci
Cocci spheres
Bacilli Rods
Vibrios comma shaped
Spirilla rigid helices
Spirochetes flexible helices
Mycelium network of long, multinucleate filaments
Palisades grid-like
Pleomorphic Organisms that are variable in shape
Which 2 cell envelope components make up the cell wall? Peptidoglycan and the outer membrane.
Fluid mosaic model The idea that membranes are lipid bilayers in which proteins float
Amphipathic contains both polar and non polar ends
Peripheral proteins Loosely connected to the membrane, easily removed
Integral proteins Not easily removed from membrane, insoluble in aqueous solutions
Hopanoids Like steroids, help stabilize membrane
Protoplast The plasma membrane and everything w/in it
Inclusion bodies granules of organic and inorganic material suspended in the cytoplasm, used for storage and reducing pressure
Where are proteins synthesized Ribosomes
Nucleoid Irregularly shaped region containing the bacterial chromosome
Plasmid small, double-stranded DNA molecules that exist independently of the chromosome
What is the Periplasmic space? area between plasma membrane and cell wall
What two substances make up peptidoglycan? N-acetylglucosamine and N-acetylmuramic acid
Which type of bacteria has teichoic acids? Gram (+)
Teichoic acids Help give gram (+) cell wall its negative charge
Braun's lipoprotein Links outer membrane to peptidoglycan
Sec-dependent Secretion dependent, the main pathway for transporting proteins across the plasma membrane
What is it called when a cell has an outer layer that is clearly defined and not easily removed? Capsule
Slime layer Zone of diffuse, unorganized material that is easily washed off a cell
Fimbriae Short, fine, hairlike appendages, thinner than flagella
Pili 1-10 per cell, larger than fimbriae, required for conjugation (sex pili)
What are the parts of a flagella? Flagellar filament, basal body, flagellar hook
Flagellar filament Part of a flagella that extends from the edge of the cell surface to the tip
Basal body Part of the flagella that is embedded in the cell
Flagellar hook Links the filament to the basal body, acts as a flexible coupling
Describe flagellar motion The flagella is shaped like a helix, which rotates the cell and moves it forward
Monotrichous One flagellum
Polar flagellum A flagellum located at one end of the cell
Amphitrichous Flagellum at each pole
Lophotrichous Cluster of flagella at one or both ends
Peritrichous Flagella evenly spread all over
What is the purpose of an endospore Survival under harsh environmental conditions
What is in the Periplasmic space? Contains hydrolytic enzymes and binding proteins for nutrient processing and uptake
Heterotroph Organisms that use reduced, pre-formed organic molecules as their carbon source
Autotrophs Organisms that use CO2 as their sole or principal source of carbon
Phototrophs Use light as their E source
Chemotrophs Obtain E from oxidation of chemical compounds, can be organic or inorganic
Cemoorganotrophs Obtain E from oxidation of organic compounds
Chemolithotrophs Obtain E from oxidation of inorganic compounds
How do bacteria obtain inorganic Fe? Siderophores
What are some examples of growth factors? Vitamins, amino acids, purines, pyrimidines
Synthetic media All components and their quantities are known
Complex media contains some components of unknown compositions
What are the types of media? General purpose, enriched, selective, differential
Enriched media Added growth factors
Passive diffusion Molecules move from an area of higher concentration to an area of lesser concentration
Facilitated diffusion Involves "carrier molecules" to increase the rate of diffusion
Active transport metabolic energy required to move substances against a concentration gradient
What are the two types of active transport? Symport, anti-port
Symport Active transport of two molecules in the same direction
Anti-port Active transport of two substances in opposite directions
Group translocation modifies molecules as they enter the cell
Permeases Carrier proteins
ATP-binding cassette transporters Active transport system, consists of 2 hydrophobic membrane-spanning domains with 2 ATP binding domains
Selective media favors the growth of one particular organism
Differential media distinguishes among different groups of microbes and permits tentative identification
Pure culture Population of cells arising from a single cell
Spread plate Spread a dilute solution containing the organism over a plate of media
Streak plate What we do in lab, use a loop to streak a small amount over the plate to achieve isolated colonies
Pour plate Original sample is diluted several times to obtain isolated organisms when poured into a plate
What are the basic structures of a monosaccharide? One carbon ring with hydrogens and oxygens bonded to it
How do bacteria use carbohydrates? As glycoproteins, which are receptors for the cell, they also form glycocalxy, which produces capsules and slime layers, also used in respiration
How do microorganisms use lipids? They use them for structure and as an energy source because of the high energy bonds present
How do microorganisms use cholesterol? Provides structure and support
How do microorganisms use phospholipids? Provide structure and protection, make up the cell membrane
What are the 3 parts of an amino acid? An amine (-NH2), carboxyl groups (-COOH) and and R group
How many amino acids are needed to make a protein? At least 30
Acid fast bacteria Resistant to simple acids, also hard to break down with anti-microbials
What form of cell division do bacteria use? Binary fission
What defines microbial growth? Increase in cellular constituents, increase in organisms size, population size or all 3
Why is the initial phase of growth called the "lag phase"? Because there is no immediate increase in population size because the cell is synthesizing new components needed for growth
What are the stages of cell growth in order? Lag phase, exponential phase, stationary phase, death phase
At what salt concentration do Halophiles grow? >0.2M
Which extremophiles grow at salt concentrations of 2M - 6.2M? Extreme halophiles
What are the 3 ways to classify bacteria with respect to pH? Acidophiles, neutrophiles, alkaliphiles
At what pH range do acidophiles thrive? 0-5.5
At what pH range do neutrophiles thrive? 5.5-7
At what pH range do alkaliphiles thrive? 8.5-11.5
What are the 5 ways of classifying bacteria with respect to temperature? Psychrophile, psychrotroph, mesophile, thermophile, hyperthermophile
Fluorescence Microscopy Exposes organisms to ultraviolet, violet, or blue light then forms an image from the resulting fluorescence
Created by: 629143505