Unit 3 Lab Exam Flashcards
Stain increase ______ needed for viewing cells
contrast
Stains = solvent + ____________
chromogen
What is the portion of the chromogen that gives the dry its color
chromophore
What is the portion of the chromogens that have charged portions that allow them to interact with cellular components through ionic and covalent bonding
auxochrome
Define simple stain
react uniformly with all microbes and only distinguish the organisms from their surroundings
What are two examples of simple stains
methylene blue and CV
Define differential stains
discriminate between various bacteria, depending upon the chemical or physical composition of the microbes
What is an example of differential stain
gram stain and acid-fast stain
Define specialized stains
designed to detect specific structures of cells such as flagella or endospores that may be present in some microbes but not others
Why do we heat fix slides for stains
cells will wash off the slides that are not heat fixed; don’t overheat as cells will be ruptured or distorted
bacilli or bacillus
rod shaped cells
cocci or coccus
spherical cells
elongated spheres
ovoid
Gram positive stains
purple
gram negative stains
pink
What is the purpose of the immersion oil with the microscope
to prevent light scattering
Size and shape of bacillus cereus; generally observed in
large and bacilli; chains
size and shape of staphylococcus epidermidis
relatively small and coccus shaped
size and shape of saccharomyces cerevisiae
larger than bacterial cells and are ovoid in shape
3 things needed to clean the microscope
all oil wiped off
10x objective lens in place
stage centered
What happens if for the gram stain you have too thick of a smear
slide is hard to destain, resulting in gram negative looking gram positive
What happens if the destaining the slide is not long enough
gram negative cells will appear gram positive
What gram bacteria are the following
S. epidermidis
P. fluorescens
gram positive
gram negative
What is the order of a gram stain
CV
Iodine
Alcohol-acetone
Safranin
What type of dyes are used for capsule stain
India ink
CV
What stain does it require you don’t heat dry or blot dry
capsule stain
What type of species doesn’t stain regularly and needs the acid-fast stain
mycobacterium
What can dye the mycobacterium cells?
treatment with cold carbol fuchsin for several hours or at high temps for five minutes will dye the cells
Define endospores
dormant cell structures produced by some species of bacteria, including those in the genera bacillus and clostridium
Endospores are extremely _____ and resist inactivation by heat, chemicals, and radiation
resilient
What dyes are used in the endospore stain
malachite green
safranin counter stain
What is the CV in the gram stain
primary stain–initially stains all cells purple
What is the iodine in the gram stain
it acts as a mordant (fixer) and forms a complex with the CV, fixing it to the cells
What is the alcohol-acetone in the gram stain
this reagent dissolved the lipids in the gram negative cell outer membrane, allowing the removal of crystal violet-iodine complex from these cells
What is the safranin in the gram stain
country stain for the decolorized cells
