Chapter 2- Tools Of The Lab Flashcards
Define media.
A nutrient used to grow organisms outside of their natural habitat.
Define inoculation
The implantation of micro organisms into or upon culture media
Define culture
The visible accumulation of micro organisms and or on a nutrient medium. Also the propagation of micro organisms with various media.
Define incubator
To isolate a sample cultural and a temperature controlled environment to encourage growth.
Give examples of clinical specimens that can be used as an inoculum’s
Blood Cerebrospinal fluid sputum urine feces
What temperature range is ideal for most pathogens?
Between 20°C and 45°C
What is the difference between pure cultures, mixed cultures and contamination?
A pure culture is a container of medium that grows only a single known species or type of micro organism.
A mixed culture is a container that holds two or more identified, easily differentiated species of micro organisms, not unlike a garden plot containing both carrots and onions.
A contaminated culture was once pure or mixed but has since had contaminants or unwanted microbes of uncertain identity introduced into it.
Media is classified by what three properties?
Physical state, chemical composition, and functional type or purpose.
Define broth and agar
Agar is A polysaccharide found in seaweed and commonly used to prepare solid culture media
What are the properties of agar that allow for it successful use in the microbiology laboratory?
Auger is flexible and moldable, and provide the basic framework to hold moisture and nutrients, though it is not itself a digestible nutrient for most micro organisms.
Define chemically defined media and complex media. Give examples of each.
Chemically defined media can come in many forms. Some media such as minimal media for fungi, containing nothing more than a few essential compounds such as thoughts and amino acids dissolved in water. Others contain a variety of defined organic or Inorganic chemicals
Complex media contain at least one ingredient that is not chemically definable – not a simple, pure compound and not represented by an exact chemical formula. (Blood, serum, etc)
Describe general-purpose media
Grows a broad spectrum, nutrient agar/broth BHI, TSH
Describe minimal media
Has few Esencial compounds – salts, amino acids – some defined organic and in organic chemicals
Describe enriched media
Fastidious microbes – it needs growth factors/nutrients
Describe enrichment media
It encourages growth of desired microbes
Describe selective and differential media
Selective media suppresses unwanted microbes, it encourages desired microbes
Differential media distinguishes colonies of different microbes it has a pH indicators
Describe reducing media
Contains a substance that absorbs oxygen
Describe carbohydrate fermentation media
It contains sugars that can be fermented, has a pH indicator, it’s in a Durham tube.
Describe transport media
Used to maintain/preserved specimens before clinical analysis. It’s used to sustain delicate species.
What procedures can be utilized to obtain a pure culture?
Aseptic technique
Define CFU
Colony forming units
How can microbes be identified?
Appearance, biochemical tests.
Briefly describe the differences in maintenance and disposal of cultures in a medical laboratory verse a research laboratory
Most medical laboratories have a strict rule about promptly and properly disposing cultures and specimens because they can pose a potential threat or hazard. Teaching and research laboratories still need a proper way to dispose of cultures and specimens however they do not do it so quick Willy. They actually maintain a line of stock cultures that represent living catalogs for study and experimentation.
List the four major laboratory safety designations. What type of protection and microbes are associated with each level?
Biosafety level – 1– non infectious bacteria.
Biosafety level – two – mild disease, difficult to contract, genetically modified organisms, lab coat gloves and eye protection necessary!
Biosafety level – three – serious or potentially lethal disease after inhalation, biosafety cabinet to prevent airborne transmission.
Biosafety level – four – high risk of aerosol transmission, severe to fatal disease. Sealed, negative pressure, exhaust air is filtered twice
What are the average sizes of viruses, bacteria, protozoan and algae?
Bacteria- 200 nm
Protozoa & algae- 3-4 mm
Viruses- 20-800 nm
What is the difference between resolution and magnification? What allows for greater resolution.
Magnification will amplify the image. Resolution is the capacity to distinguish to adjacent points. An oils immersion lens will allow for greater resolution.
Defined re-fraction
The bending of light as it passes from one medium to another with a different index of reflection
What is refractive index and how does it relate to contrast?
Reflective and DAX refers to the degree of bending that light undergoes as it passes from one medium such as water or glass to another medium such as bacteria cells. The higher the difference and reflective indexes – the more bending of light – the sharper the contrast that is registered by the microscope and the eye.
What is total magnification?
The objective lens times the ocular lens.
For example The total magnification of a specimen that’s being viewed through an ocular lens with a 10 X magnification and a objective lens with a 100 X magnification would be 1000
What is the purpose of oil immersion
To increase resolution. The oil immersion lens will capture light that would otherwise be lost to scatter and reducing scatter increases resolution
No the parts of a light microscope
Ocular is the eyepiece the body holds up the eyepiece the nose piece is what attaches to the objective lenses the mechanical stage is what will hold the slide the arm is the back of the microscope the aperture Diaphragm controls how much light is let in. The babies will hold the field diaphragm lever which is how the light shines through the course focus adjustment knob is on the outside and the fine focus adjustment knob is on the inside both of those are on the side of the arm the stage adjustment knobs are going to be on the side of the stage attached.
List the types of microscope he and what light they utilize
Visible light microscope – brightfield, dark field, phase – contrast, differential interference.
Ultra violet rays microscope – fluorescent, confocal.
Electron beam microscopic – transmission electron microscope, scanning electron microscope.
What is the difference between Lightfield and dark field microscope he? What accounts for this difference?
The difference is that the dark field microscope contains a stop which is applied to the condenser. The stop blocks all light from entering the objective lens except peripheral light is reflected off the side of the specimen itself.
Compare and contrast phase contrast microscopy differential interference contrast microscopy Which allows for a more detailed picture?
They both use light intensities to pass through the object in sept always the difference is that the D I C has additional refinements including two prisms that I had contrasting colors the image so the DIC microscope produces a much better image.
Describe fluorescent microscopy
The fluorescent microscope especially modified with an ultraviolet radiation source and a filter that protects the viewers eye from injury. The name of this microscope originates from the use of certain dies and minerals that show fluorescence. For an image to be formed the specimen must be coded with a source of fluorescent fluorescence microscopic he has its most useful applications in diagnosing infections caused by specific bacteria protozoans and viruses
Describe TEM and SEM
TEM is transmission electron microscope ups and they are the method of choice for viewing the detailed structure of cells and viruses. Because electrons cannot penetrate thick preparations the specimen is sectioned into extremely thin slices. The slices are stained or coated with metals that will increase contrast.
S EN is the scanning electron microscope and it provide some of the most dramatic and realistic images this is instrument is designed to show an extremely detailed three dimensional view of all kinds of objects that object is created with metal coated special specimen with electrons while scanning back-and-forth over it
Why must a specimen be prepared?
Safety, appropriate dye used to allow best view
Define smear
Spreading a thin film made from a liquid suspension of cells on a slide and air drying it
How is a microbe fixed to a slide?
Putting the slide face up through the flame three or four times that will simultaneously kill the specimen and secures it to the side
What is the difference between a basic and acidic die? Which one is in anion? Cation? Which one is used for positive staining? Negative staining?
Cation is basic and they have positive charge so they are used for negatively charged cell parts
Anion is acidic and they have a negative charge so they will attract positively charged cell parts
What is the difference between a simple stain and a differential stain?
Simple stains require only a single guy and an un-complicated procedure. Differential stains used to differently colored dyes caught a primary die and the counterstain to distinguish between cell types or parts.
What is a mordant?
The mordant in the Gram stain is iodine.
Explain the process of grand staining. What color are gram-positive organisms? What color are Graham negative organisms?
Prepare heat fix slide.
Drop a few drops of crystal violet stain on to the fixed slide.
Drop a few drops of iodine and let stand for 20 seconds. This will fix the crystal violet to the the peptidoglycan if the molecule is gram positive
Drop decolonizer onto slide
Drop contrast dye onto slide (counterstain)
View under microscope
Gram positive will be purple
Gram negative will be pink
What is acid fast? What are two genera of acid-fast bacteria? Explain acid-fast protocol. What color are acid-fast bacteria? Non-acid fast bacteria?
Acid-fast bacteria is pink. Non-acid-fast bacteria is blue. This stain is used to detect myco-bacterium tuberculosis in specimens. These bacterial cell walls hold fast to the dye (carbon fuchsia) even when washed with an acid or alcohol containing substance
Describe endospore stain.
It is similar to the acid-fast stain because a guy is forced by heat into resistant bodies called spores. The stain is designed to distinguish between spores in the cells that they come from. Endospores will show up red and vegetative cells will show up blue
Discuss capsule staining
It is often negatively staying with India ink or it may be demonstrated by special positive things. The background of the stain is maroon while there are light pink cocci with another circle inside the cocci
What are the five I’s of culturing microbes? Describe each.
Inoculation, incubation, isolation, inspection, identification.
Inoculation is when the sample is placed into a container of sterile medium containing appropriate nutrients to sustain growth.
Incubation is when an incubator is used to create the proper growth temperature and other conditions.
Isolation is when microbes may take the form of separate colonies on solid media or turbidity in broths.
Inspection is when the colonies or broth cultures are observed macroscopically for growth characteristics color, texture, size, that could be useful in analyzing the specimen contents.
Identification is the major purpose of the five I’s. Information used an identification can include relevant data already taken during initial inspection and additional test that further describe and differentiate the microbes.
