Micro Midterm Lab Practical Flashcards
Where do you dispose... Used glass test tubes Used glass slides Broken glass Used latex gloves Paper towels used in bench disinfection Uncontaminated trash Contaminated Petri plates Qtip swabs used to clean microscopes
Discard racks Disinfectant basin Cardboard broken glass receptacle Autoclave trash Regular trash Regular trash Autoclave trash Regular trash
Function of ocular
The eye piece that Magnifies an image ten times
Function of objective lenses
Magnify an image at varying amounts
Function Of Condenser
Concentrates the light beam onto the specimen
Function of the course focus knob
Refine resolution of images on a larger scale
Function of iris diaphragm lever
Enlarges the iris diaphragm to let increase light intensity
Function of mechanical stage knobs
Allows you to move the specimen around to find things
Function oF Condenser height adjustment knobs
Adjust. Height of condenser
Function of condenser centering screws
Centers the condenser
Function of diopter ring
Allows you to focus the individual eyepiece To your eye.
Function of base diaphragm
H
Function of fine focus knob
Adjust the resolution at a smaller scale
Function of stage clip
Hold slide. In. Place
Describe the steps to cleaning. A microscope properly
- Rotate nosepiece to 5xs objective
- Remove excess. Oil from oil immersion objective with qtip
- Clean all lenses with lens cleaner and qtips and dry
- Turn down rheostat and turn off light switch
- Replace cover
Explain. Purpose of using immersion oil who using 100x objective
It minimizes the amount of light that is refracted or lost and therefore. Increases resolution of the image.
Name two major types of microscopes that have been developed and. And name the difference between. These two types. Of microscopes
Compound microscope- uses light
Electron microscopes- uses electrons to produce. Image
List 4 examples. Of compound microscopes and star the example you will use in lab
Phase contrast
*bright field
Dark
Fluorescent
Define magnification
Ability of. Microscope to enlarge an object
Name two magnifying lenses. In a compound microscope
Objective lens
Ocular/eyepiece lens
List. Common names. And the magnification of the four objectives you will. Use in this. Lab
Scanning. Objective- 4x
Lower power objective- 10x
High power. Objective- 40
Oil immersion objective-100x
How is total magnification of an object calculated?
Ocular x objective = total magnification
State the. Two. Factors that. Determine. How we’ll an object. Can e seen with a. Microscope
Resolution and magnification
Define. Resolution
Describes. How clear specimen will appear when viewed through the lenses
Name the. Two components that influence the resolving. Power of. A microscope
Numerical aperture and. Wavelength of light
Define refractive index
Measures. How. Lens. Is. Able to bend light
Function off iris diaphragm
Regulates intensity of light entering. Lenses
State three steps to achieve adequate lighting when the. Oil immersion objective is. Used to. View a specimen
- Condenser raised to highest. Opposition
- Iris and bars diaphragm are all the way open
- Rheostat turned ups s much as I can stand it.
Define ubiquitous
They are everywhere
Define pure culture
Isolation of a single strain of bacteria
Define colony
A group. Of bacteria that descend from a single. Parent that reproduced asexually and are identical. To each other
Define. Turbidity
Cloudiness that indicates growth
Define media
Nutrient material. Suitable for cultivation of micro organisms.
Define inoculum
Transfer a sampling of umpire culture
Define aseptic technique
Techniques developed to prevent contaminating microbes from entering cultures.
Why is it important to allow the loop. To. Cool before obtaining your bacterial sample?
If we used a hot loop, we would kill the bacteria we are. Trying to transfer
Why is it. Important. To hold the test tube cap with your little finger while taking your bacterial sample?
To prevent contamination
Why is. It important. To. Obtain a pinpoint amount. Of sample as. Your inoculum?
So ewe don’t get to much so the bacteria can stain and Decolorize properly
Why are. The agar plates labeled on the bottom?
Why are they inverted when incubated?
So we can see the writing, and it stays I with the agar, and. Des not move when the lid is turned.
To prevent condensation onthe media
What is the. Criteria used to describe a bacterial colony?
The shape, margin (edge), elevation, texture, and pigment
State three ways that lab Media. CAn become Contaminated AND give specific. Aseptic techniques that can be used to. Prevent that type of. Contamination.
A. Surface of skin- wear gloves and wash hands
B. unsterile equipment- sufficiently sterilized don’t use used stuff
C. Exposing. Media to contaminated air- put cap back on ASAP, hold lid with little. Finger.
Describe the. Steps involved. In labeling a test tube
Get labeling tape write initials. Ont it and stick it onthe. Tube
Describe all steps involved in labeling a Petri plate
Label he bottom with name or. Initials
NEVER ON THE LID
Describe all steps involved in incubating a Petri plate
Stack agar plate lid side down so condensation forms on the lid not on the he media where bacteria grow.
List in order the reagents used in the traditional gram stain procedure
Crystal violet
Iodine
Acetone alcohol
Safranin
State the function of a each reagent
Crystal violet- primary dye, stains all the he bacteria on the slide
Iodine- mordant, binds with crystal bviolet and makes large molecules that get stuck under gram positives large cell wall
Acid alcohol-decolorizes those bacterial that don’t have large walls
Safranin-secondary dye, stains all remaining bacteria
Explain the mechanism of the grams stain (why gram negative cells lose the primary dye during decolorization)
The decolorizer breaks up the lipids of membranes, gram negative cells have an outer membrane and then the dye is released.
What color are gram positive and gram negative cells? What are there two shapes?
Gram positive are purple
Gram negative are pink
Cocci-round
Bacilli-rod
Explain the difference between a simple stain and a differential stain
Simple only uses one dye, and tells us shape size configuration
Differential stain uses two dyes and tells us all that plus something else
Why are basic dyes used in the he gram stain?
They have an overall positive charge which is attracted to the negatively charged bacteria
Explain the difference between the cell wall composition of gram negative bacteria and gram positive bacteria.
Gram positive have a large layer of peptidoglycan
Gran negative bacteria have an outer cell membrane with a thin layer of peptidoglycan underneath.
What is the importance of allowing the smear to air dry?
So get he cell walk doesn’t burst due to boiling insides and they stay intact
What is the importance of decolorizing the smears one at a time?
Most critical and difficult step, no set time for it so you have to be careful and watch carefully
State the two genera that are idtified using the acid fast stain. State diseases caused by acid fast bacteria
Mycobacterium- tuberculosis and leprosy
Nocardia- nocardiosis and cryptosporidiosis (diarrheal disease)
What color are acid fast organisms and non acid fast organisms
Acid fast are pink
Non acid fast are blue
Explain why certain organisms are acid fast
Acid fasts organisms have really waxy walls that prevent decolorization
Differentiate between the decolorizer used in he the acid fast stain and the gram stain.
Gram-acetone alcohol
Acid fast- acid alcohol
State, in order, the three reagents used in the acid fast stain.
Carbolfuchsin
Acid alcohol
Methylene blue
Why is the acid fast stain considered differential stain
There are two stains or dyes. Used
Distinguishes 2 groups of organisms tells more than just size shape and arrangement
What is the difference between the Ziehl-Neelsen stain and the kinyoun stain?
Zn uses steam to penetrate my colic acid
K uses very cone rotated dye, hard heat fixing and longer exposure tim.
Name two medically important genera of bacteria that produce endospores
Bacillus and clostridium
What color are the vegetative cell ands endospore
Endospore is green
Vegetative cell is red
Describe the process paused to stain the relatively impermeable endospores
Heat and extended stain time
Name the dyes used in huge schaeffer-Fulton spore stain
Malachite green
Safranin
Define vegetative cell
Metabolically active, replicating cell
Define sporogenesis
Formation. Of endoscopes
Define germination
Reverting from endospore to vegetative cell
Why are endospores considered he most resistant life form known?
Can remain dormant indefinitely
Resistant to antibiotics, most disinfectants, radiation, boiling, and drying
List five medically important endoscope producing bacteria and their associated disease
- Bacillus anthracis-anthrax
- Clostridium botulinum- botulism
- Clostridium difficile- toxic enterocolitis
- Clostridium perfringens- gangrene/food poisoning
- Clostridium tetani- tetanus
What is the difference. greens positive stain and a negative stain?
Negative- stains everything except what we want to see
Positive- stains object we want to see
What does a bacterial capsule look like in a negative stain?
White halo
Using Anthony’s stain, the background will be colored ? And the capsule will be colored ?
Dark blue and light blue/white
State two advantages of using a negative stain versus a positive stain.
- See he microorganism alive, don’t have to heat fix it
2. Can see things you wouldn’t with a + dye
Explain why nigrosin and India ink are commonly used in negative stains
Hey are acidic (negatively charged) and are repelled by the negative charged contents if cell wall
Differentiate between a capsule and a slime layer
Capsule- firmly attached to cell all, firm in shape
Slime- loosely attached, irregularly shaped
State. Three ways a capsule contributes to the virulence of a bacteria
- Sticky so attatchment to skin and mucous membranes
- Sourced of nutrition
- Helps avoid phagocytosis
State two differences between the smear preparation for a gram stain and a capsule stain
No heat
No rinse with water
Define reducing agent
Binds to oxygen and turns it into water
Why is thioglycollate a semi-solid agar?
Contains solid agar but because of water produced by reducing agents, it becomes more liquified
What are the damaging by products of oxygen during cellular respiration?
Superoxides and peroxides
Name three enzymes that neutralize the damaging effects of suoeroxides and peroxides
Catalase, perixidase, and superoxidase dismutase
What is the difference between an aerobe and an anaerobes?
Aerobes have enzymes that break down toxic forms of oxygen and their intermediate by products, they use oxygen as the final member of the etc
Anaerobes have no tolerance for oxygen cuz have no enzymes to break down oxygen byproducts, Don’t use oxygen as final member of etc
How does the candle jar achieve an atmosphere to grow microaerophilic, capnophilic organisms
A flame is lit which consumes oxygen and produces carbon dioxide
How does the gas pack jar achieve an anaerobic atmosphere?
Hydrogen gas is real eased whew aged and palladium catalyst are in the lid, hydrogen combines with oxygen and turns to water.
Which type or organism grows equally well in all types of oxygen concentrations?
facultative anaerobes
How does the thioglycollate both grow anaerobic bacteria as well as aerobic bacteria?
It contains a small amount of agar which helps retard oxygen diffusion. So oxygen can’t get through alo of it, so oxygen at the top, not oxygen at the bottom
What organisms can have any manhunt of oxygen present?
Facultative anaerobe
What organism require 20% oxygen?
Obligate aerobes
What organisms can not have any oxygen present?
Obligate anaerobes
Which organisms like co2
Which ones like a lower percent of o2?
Capnophile
Microaerophile
Describe the genes located onthe. Pglo plasmid
Ara-c- produces a represent protein
GFP- produces the protein that allows it to glow
BLA- produces the antibiotic resistant protein
Describe the protein encoded in the pglo series
Ara-c repressor protein
Green fluorescent protein
Beta lactamase
Define competent and describe two methods to make e. Coli competent
Able to take up DNA from an environment!
- Growth in presence if calcium chloride
- Extreme temperature changes
Explain the regulation mechanism of the green fluorescent protein gene expression
Ara-c repressor protein blocks transcription and translation of GFP
Arabinose moves Ara-c out of the way
Which gene allows jellyfish to glow in the dark?
GFP
What is the relationship between a gene and a protein?
A gene is a piece of DNA that codes for making a protein
Compare and contrast chromosomal DNA and plasmid
Chromosomal DNA carry genes needed for heriditary characteristics essential for bacterial growth and reproduction
Plasmid are small pieces of circular DNA that has nonessential info on it
Compare the Kirby-Bauer test with the MIC test
Kb- tells us which antibiotic will work
Mic- tells us the dosage needed
State the. Principle of the beta-lactamase test
Interpret results
Does the bacteria produce beta lactamase
Red-negative, no beta lactamase produced, sensitive to antibiotics
Yellow- positive, beta lactamase produced, resistant to antibiotics
State media used for the antibiotic sensitivity test
Mueller-Hinton agar
Define antibiotic
Chemicals produced by microorganisms that can inhibit growth of other micro organisms
Define MIC
Minimal inhibitory concentration test
Lowest concentration of an antibiotic to inhibit growth of test organism
Define e-test
Plastic coated strip that is a combination of mic and Kirby Bauer tests
What are the he disadvantages to. Using abroad-spectrum antibiotic?
Contributes to escalating resistant bacteria
Wiles out normal flora so super infections can take place
List eight factors that must. R controlled in reorder to standardize the Kirby Bauer test
- Rate if diffusion of antibiotic
- Stability of antibiotic
- Ph of culture medium
- Depth of culture medium
- Inoculum density
- Incubation time
- Incubation temp
- Concentration of antibiotic
What does t he antibiotic test result sensitive indicate about the test organism?
The antibiotic works. On the pathogen
