Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
37 Cards in this Set
- Front
- Back
- 3rd side (hint)
what two parts of the microscope are used to carry or support the microscope?
|
arm and base
|
|
|
what are the three optical parts of a microscope
|
abbe condenser, ocular lenses, objective lenses
|
optic means to see
|
|
list the four objective lenses by the name, color, and the magnification for each.
|
scanning objective: red: 4x
low dry objective: yellow: 10x high dry objective: blue: 40x oil immersion: white: 100x |
|
|
what is the function of the abbe condenser?
|
collects and condenses the light
|
|
|
what is the function of the iris diaphragm?
|
lever that controls the abbe condenser. It controls the amount of light going out of condenser.
|
|
|
what are the four microscopic morphologies of bacteria that we talked about in lab?
|
cocci, coccobacilli, bacilli, spiral
|
|
|
define parfocal lenses
|
once objective is in focus, you should be able to go from one objective to the next with little to no focusing needed
|
|
|
what is the purpose of oil when using an oil immersion objective?
|
improving resolution by preventing the scattering of light
|
|
|
what are the three main steps when cleaning your microscope to be put away?
|
1) clean objective lenses yellow, blue, white
2) clean oculars with alcohol swab and then polish with lens paper 3) take alcohol swap and clean the stage |
|
|
how is total magnification determined?
|
ocular magnification (10x) multiplied by objective magnification (4x, 10x, 40x, 100x)
|
|
|
if 5x instead of 10x oculars were used with the same objectives now on your microscope, what total magnifications would be achieved for EACH ONE?
|
Red: 5x * 4x = 20x
yellow: 5x * 10x = 50x blue: 5x * 40x = 200x white: 5x * 100x = 500x |
|
|
explain why flaming the inoculating needle prior to and after each inoculation is essentail during culturing?
|
to ensure that the needle is sterile and won't contaminate the bacteria
|
|
|
explain why holding the test tube cap with you "pinky" finger with the same hand that is holding the needle is essential during culturing?
|
gives your hand holding the tube more freedom to move safely without fear of damaging the test tube or the bacteria within it.
|
|
|
explain why cooling the inoculating needle prior to touching the bacteria in the culture is essential during culturing?
|
if it is still hot, it will burn and kill the bacteria
|
|
|
explain why flaming the openings of the tubes immediately after uncapping and before recapping is essential during culturing?
|
to protect the inside, the bacteria, from contamination when the needle goes in to the tube.
|
|
|
define media
|
nutrient rich base, used to house bacteria during incubation
|
|
|
what is agar and where does it come from?
|
agar is a complex polysaccharide extracted from a certain solidifying substance made from seaweed
|
|
|
list the three ways to determine whether culture media given to you are sterile before you use them
|
-broth should be clear before you use it
-slants or plates should have no colonies present -run controls on newly made media |
|
|
why should you hold open culture tubes at an angle?
|
to avoid the rush of air contamination
|
|
|
what are two possible errors which could have occurred if you find your subcultures had no growth after incubating for 48 hours?
|
-you didn't cool the needle enough before inoculating it
-you completely forgot to inoculate it |
|
|
what are two things to remember for safely using bunsen burners?
|
-never reach across the flame
-light match first before turning on gas |
|
|
why is sheep blood agar used as media?
|
because the bacteria will grow in the sheep blood similarly to the way it would grow in human blood, so we can get the results we need without putting ourselves at risk for contracting blood borne diseases. It also provides lots of nutrients for the bacteria to feed off of as it grows.
|
|
|
what are the five characteristics of bacterial colonial morphologies?
|
-texture/consistency
-density -color/pigment -size -shape |
|
|
why should a Petri dish not be left open for any extended period of time?
|
it could become contaminated
|
|
|
what does streaking for isolation mean?
|
it means that you take a small sample of whatever it is you want to examine further, streak it in a media, draw lines in media, spreading out the sample, which therefore enables individual colonies to grow, creating uncontaminated samples to be observed
|
|
|
what is the purpose of inverting (keeping agar side up) plates during incubation?
|
prevent condensation build up that would ruin culture
|
|
|
what is normal flora?
|
normal bacteria that grows on different mucosal surfaces of the body
|
|
|
list four sites where normal flora occurs in the body
|
mouth, skin, throat and intestinal tract
|
|
|
what color is SERRATIA when grown at room temperature?
|
red
|
|
|
define pure culture and mixed culture. Which one should you use when performing any testing on bacteria?
|
pure culture: only have on type of organism that your isolating
mixed culture: more than one organisms present in sample you're streaking from -you should use pure culture |
|
|
what 2 things should you always do to enhance the isolation of bacteria from a colony?
|
-use a firm touch on the colony: NO SCOOPING
-after primary inoculation, flame and cool your needle before streaking your bacteria |
|
|
list the four main steps in the gram stain procedure and tell the purpose of each step
|
-flood slides with crystal violet for 30-60 seconds: primary stain
-flood slide with gram's iodine for 30-60 sec: mordant-keeps stain on -decolorize with 95% Ethanol: decolorization of gram negative cells -flood slide with safranin for 30-60 sec: counterstaining gram negative cells |
|
|
what are the chemical differences between the cell walls of the gram positive and gram negative bacteria that might explain difference in the rate of decolorization?
|
Gram positive cells have a VERY thick cell wall made of peptidoglycan that can not be permeated by the alcohol, therefore the purple color from the crystal violet stain will remain on the bacteria
-whereas a gram negative's wall is much thinnger and made of lippolyssacharides, which are penetrable by the alcohol, because of this, the color can be taken away in great quantities on a gram negative cell |
|
|
if the mordant was omitted, how would the staining results be affected?
|
the initial stain, crystal violet, wouldn't stick to the bacteria as well, causing the final colors of the bacteria (gram positive and negative) to be much more similar
|
|
|
should the primary stain and the counterstain be of contrasting colors? why or why not?
|
yes, that way the organisms the stains stick to can be easily identified and separated when examined through a microscope
|
|
|
define gram variable, and then list two reasons why gram variability can occur.
|
there are both gram positive and gram negative present on the slide
1) the alcohol "overdecolorizes" the organism, this happens because the slide was made too thick 2) old bacterial cells (older than 48 hours); they begin to die and disintegrate at this time |
|
|
which step in the gram stain is the most critical and why?
|
3rd step (decolarization with 95% Ethanol-Ethyl Alcohol: without it, it would be practically impossible to discern, when observing the organism through a microscope, whether it is gram positive or gram negative. This would be caused by the bacteria having been stained repeatedly without any rinsing of the color.
|
|