Chapter 4 Flashcards
coccus
sphere
bacillus
rod
three main shapes of bacteria
coccus, bacillus, spiral
small drop of liquid spread on the slide
liquid culture
small colony piece mixed with a drop of water
solid culture
Air drying purpose
preserves the microorganisms shape and arrangement
purpose of heat fixation
kills microorganism and causes it to adhere to slide
the dyes used in staining are usually
salts
a salt contains
a positively charged cation and a negatively charged anion
the colored portion of the dye
chromophore
what is the chromophores purpose
binds to chemicals in cell structures via covalent/ionic bonding
procedures that only use one dye that is basic such as crystal violet or methylene blue
simple stain
what is the purpose of simple staining
to identify the shape, structure, and arrangement of bacteria
simple stain steps
- flood smear with dye for 30-60 sec
- rinse with water
- blot dry
uses two or more dyes
differential stain
purpose of differential stain
to distinguish different cells, structures or gram type
who developed gram stain
hans gram
steps to gram stain
- apply the primary stain crystal violet (all cells with be purple)
- flood smear with mordant like iodine (traps color into the peptidoglycan of gram + cells)
- rinse away with decolorizing agent (washes away the dye from the top of the gram - cell)
- apply counter stain safranin (provides contrasting color to primary stain)
removes water from liquid crystal violet turning it into solid crystals
mordant
color of gram +
purple
color of gram -
pink
gram stain works significantly better on
younger cells
waxy substance on some bacteria
mycolic acid
some myobacterium causes
tuberculosis and leprosy
Steps to acid fast staining
- primary stain, flood smear with carbolfushsin under heat which will melt the solid wax layer
- rinse with decolorizing agent, which will remove stain from non acid fast cells
- counter stain with methylene blue
results of acid fast stain
myobacterium (acid fast) = red
non acid fast = blue
what bacteria causes endospores
bacillus and clostridium
endospore bacteria causes diseases such as
anthrax, gangrene, tetanus
developed to specifically stain endospores
schaeffer-fulton or endospore stain
steps to endospore staining
- primary stain with malachite green with heat (heat opens up pores in endospore)
- decolorizing agent which causes vegetative cells to be clear and endospore to be green
- counterstain with safranin (turns vegetative cells red)
what is the decolorizing agent in endospore staining
water
stains used to reveal specific microbial structures such as capsuels
negative staining
staining steps for a negative stain
- use primary dye to stain bacteria (crystal violet) this will stain bacteria except the capsule
- stain background with an acidic or - charged dye like india ink (will repel the cell membrane and capsule)
negative stain results
background = pink
bacteria = purple
capsule = white halo
acidic dye in negative stain
india ink
primary stain in negative stain
crystal violet
staining that targets bacteria and flagella
flagellar staining
in flagellar staining what is mixed together to be used as primary stain
primary stain and a mordant
combination of primary stain and mordant allows the dye to be
less soluble, increases size and colorizes flagella
the ability to distinguish two objects or points that are close together
resolution or resolving power
difference in the intensity of two objects or the object and its background
contrast
describe a simple microscope
- one lens
- less magnifying power, less resolving power
-cannot distinguish between two objects
compound microscope characteristics
- series of lenses
- have objective and ocular lenses
- has a condenser
narrows beam of light from the illumination exit and focuses it directly on speciman
condenser
total magnification
objective lens x ocular lens
used to view bacteria, viruses, internal cellular structure, molecules, large atoms
electron microscopy
a beam of electrons is transmitted through the speciman
electron transmission microscopy
In TEM, electrons interact with what structures
internal (ribosomes, or inclusions)
a beam of electrons scans the surface of the speciman
scanning transmission microscopy
describe SEM
- coated with gold or platinum and placed into vacuum
- used to view morphology or 3d surface of speciman
describe TEM
- speciman is dehdryated, chemically fixed, and embedded into plastic and placed in a vacuum
the science of classifying and naming organisms
taxonomy
the assigning of organisms to taxa based on similarities
classification
determining that an isolated organism belongs to a particular taxon or group
identification
rules of naming an organism
nomenclature
