• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/77

Click to flip

77 Cards in this Set

  • Front
  • Back
liquid culture media are used for?
growing large numbers of bacteria in a short period of time.
semi-solid culture media are used for?
motility studies
solid slant culture media are used for?
store cultures of various periods of time
solid plate cultures are used for?
isolate individual bacteria from a sample.
simple stains
colour all bacterial cells in a similar way (e.g. methylene blue)
differential stains
divide bacteria into separate groups based on staining properties (e..g gram stain)
phase-contrast microscope
allows the visualization of cels without staining
bright field microscopy
used for the examination of stained cells using a compound light microscope.
oil immersion is necessary because
oil has the same reflective index as the glass slides.
gram positive cells strain?
purple
gran negative cells stain?
pink
heat fixing
kills the organisms and coagulates proteinaceous substances of cells which fastens the organisms to the slide.
primary stain
crystal violet is the primary stain in the gram staining procedure.
mordant
Gram's iodine. the crystal violet and gram's iodine will form a complex which increases the interaction of the dye and the cell so the dye binds more tightly to the cell.
differentiation step in gram stain
wash with 95% alcohol will turn gram-negative cells colourless while the gram-positive cells remain purple
counter stain
aqueous fuchsin stains gram-negative cells pink
basic stains
attracted to the opposite charge and color negatively charged bacterial cells (e.g. crystal violet, methylene blue, and safranin)
acidic stains
repelled by like charge and color the background surrounding negatively charged bacterial cells, so you can see the cells in outline (e.g. congo red, nigrosin, india ink)
blood agar
differentiates bacteria on the basis of blood cell hemolysis
beta-hemolysis
bacteria completely lyse red blood cells, resulting in a clear area around colonies
alpha-hemolysis
bacteria partially lyse red blood cells, resulting in a greenish discoloration around colonies.
gamma-hemolysis
bacteria do not lyse red blood cells, so the appearance of the agar remains the same.
spectrophotometer
measures the turbidity of a broth culture for estimating the number of bacteria in a culture.
optical density
the cell concentration is proportional to the amount of light scattered. both living and dead cells are measured.
standard plate count
a series of dilutions of a culture is plated. only viable cells are counted.
violet red bile agar
selective and differential medium that selects for coliform organisms, and the presence of coliform organisms may indicate fecal contamination in water or dairy products.
why are blanks necessary for spectrophotometer
coloured molecules absorb light, so a blank solution same as the one cells are suspended in are used to calibrate the spectrophotometer.
the samples should be measured in order of ____ for spectrophotometry.
increasing concentration
adsorption
first step in the bacteriophage infective process. the attachment of a specific phage to a receptor site on the bacterial cell.
injection
insertion of phage nucleic acid into the host bacterial cell
4 steps in bacteriophage infective process
adsorption, injection, replication, and lysed.
charged pipette
bacteriophage adhere to glass, and pipettes must be charged by pipetting the solution up and down a least three times.
how are microorganisms identified?
macroscopic morphology, microscopic morphology, and metabolic tests
catalase test
when drops of a diluted solution of H2O2 are added onto bacteria containing catalase, bubbles of O2 rapidly appear. these bubbles indicate the presence of catalase and denote a positive test.
oxidase
determines if bacteria have cytochrome oxidase. when cytochrome oxidase adds electrons to the oxidase reagent, the reduced form turns dark blue to purple within seconds.
mineral oil
create an anaerobic atmosphere for API-20E
citrate utilization test
if the bacteria utilize citrate, the byproduct CO2 combines with Na+ in the medium to form NaCO3, turning the pH indicator from green to blue (positive test).
DNase Test
if the bacteria secreted DNase. no large DNA molecules remain around the growth and a clear zone is observed (positive test).
bile esculin agar
bacteria utilize esculin in the presence of bile produce a product that reacts with the ferric citrate in the medium, turning it from yellow to dark brown.
fermentation tubes
heterotrophic bacteria often use sugars in fermentation pathways, producing acids, alcohols, and gases. acid production turns the medium from pink to yellow, and gases are trapped in an inverted tube in the medium
gelatin hydrolysis test
some bacteria can hydrolyze gelatin with the extracellular enzyme gelatinase, causing the gel to liquefy.
indole
some bacteria can degrade tryptophan to pyruvate, producing indole as a byproduct. When Kovac's reagent is added, it reacts with indole and form a red layer at the top of the tube.
MR
products of mixed-acid fermentation of glucose include significant amounts of organic acids. these acids lower the pH of the medium and when the pH indicator methyl red is added, it remains red in color (positive test). when less acid is present, the color may be orange or yellow (negative).
motility
motile cells with flagella swim away from the stab and non-motile bacteria will grow only along the stab.
nitrate reduction
if nitrite ions are produced, reagent A and B turns the medium pink or red (positive). in the absence of color change, either the nitrate ions were not reduced to nitrite ions (true negative test), or the nitrate ions were completely reduced to molecular nitrogen. zinc is added to check whether the nitrate ions were completely reduced to molecular nitrogen, which which case no color change is expected (positive).
triple sugar iron (TSI)
if bacteria ferments lactose, sucrose, or glucose, pH decreases and the medium appears yellow. if a bacterium can reduce thiosulfate, ferrous ions in the medium will combine with sulfide ions to form black precipitate.
TSI yellow slant yellow butt
glucose and lactose and/or sucrose were fermented
TSI red slant and yellow butt
only glucose was fermented
TSI red slant and red butt
none of the sugars were fermented, and not a member of the Enterobacteriaceae
TSI cracks or bubbles in yellow agar
gas was a byproduct of fermentation
TSI black precipitate in butt
H2S was produced
urea test
urease producing bacteria converts urea to carbon dioxide and ammonia, which raises the pH and turns media pink.
VP
fermentation of glucose via butanediol fermentation produces acetoin, which reactions with VP reagent in the presence of O2 to form a red product.
MacConkey Agar
crystal violet and bile salts select for gram-negative bacteria. lactose is added to make the medium differential. bacteria that utilize lactose will have pink to red colonies, while non-lactose fermenting bacteria will have colorless colonies.
DNA can be transferred between prokaryotic organisms in three ways.
transformation, transduction, and conjugation.
transformation
uptake of naked DNA by recipient cells.
Acinetobacter calcoaceticus
competent throughout exponential growth and its use obviates the preparation of competent cells.
wildtype
strain of bacteria isolated from nature or the usual form of a gene
auxotroph
organism that has developed a nutritional requirement through mutation.
sodium dodecyl sulfate
solubilizes the outer cell wall
EDTA
helps in cell lysis and binds the Mg2+ required by DNA degrading enzymes and thus protecting them.
ethanol
precipitates DNA
sodium acetate
neutralizes DNA's negative charge, allowing easier precipitation
Tris HCl
buffer for redissolving precipitated DNA.
plasmid DNA separated from chromosomal DNA on the basis of?
size and conformation (degree of supercoiling)
alkaline lysis method
DNA is denatured with NaOH and SDS at alkaline pH.
KOAc
neutralizes NaOH in alkaline lysis. chromosomal DNA, due to its large size, cannot reanneal and becomes trapped in the K/SDS complex. the renatured plasmid remains soluble in the solution and can be found in the supernantent.
restriction endonucleases
enzymes that recognize and cleave double-stranded DNA at specific palindromic nucleotide sequences.
agarose gel electrophoresis
a simple and effective method for separating, identifying, and purifying DNA fragments.
the rate of migration through agarose gel is affected by?
voltage, size, and shape.
supercoiled
covalently closed circular, most compact form and will migrate the farthest
linear
duplex, migrate somewhat slower then the supercoiled form
nicked
relaxed or open circular, migrate the least distance
RISK Group 1
Not known to consistently cause disease in healthy individuals
RISK Group 2
Associated with human disease hazard i.e. cuts, injury, ingestion exposure
RISK Group 3
Indigenous or exotic agents with potential for aerosol transmission, disease may have serious or lethal consequences
RISK Group 4
Dangerous/exotic agents which pose high- risk of life-threatening disease , aerosol- transmitted lab infections or related agents with unknown risk of transmission