LabEx1:Understanding material used in micrscope Flashcards
- Advantages: easy to use, readily and relatively inexpensive, commonly used
- Disadvantage: can recognize cells but not finer details; cells lack contrast with water
- Contrast:Difference in intensity between objects and it’s background
Light or bright field microscope
100x objective lens requires ?
Oil immersion
What does oil immersion do the lens?
- Oil displaces air, avoids refraction
- oil increases numerical aperture, thus improves resolution because more light rays are gathered into lens to produce image.
___________ is bending of lights ray as it passes from immediately to another
Refraction
Refraction prevents
Light from entering the small opening of the high powered objective lens
Aperture size of the objective lens decreases with increased magnification; which allows?
Less light to enter the objective lens
- contrast special condenser to enhance contrast when viewing object
- permits examination of internal structures
- good for viewing objects without staining (as cilia and flagella)
Phase contrast
- objects look bright against dark background
- contains special condenser with opaque disc to block light
- good for viewing motility of organisms and examining microbes that Cannot be stained or they get distorted by staining procedures
Dark field
- normally use to visualize organisms that fluoresce
- often cells are treated with fluorescent dyes then observed for fluorescence
fluorescence microscope
- uses electromagnetic lenses, electron and fluorscent screen to observe specimen instead of glass and light
- wavelength of electrons is approximately 1000x shorter than visible light
- much higher resolution is obtained and greater detail can be observed
electron microscope
_____ technique of adding dyes to color specimen (microbes, cell, tissue etc)
Functions: provides contrast and increases resolution for light microscope
-allows visualization with ease
-reveals internal and external structures
-aids in classification and identification
STAINING
_______ thin film of material containing biological material or microorganism spread over the surface of slide.
importance of ________
_________ thick - trouble seeing individual cells
_________ thin - you may find no organism
too much stirring - disrupts cell arrangement
SMEAR
________ adherence of microorganism to slide
- accomplished by either heat or chemicals (cold alcohol acetone mixture)
- advantages: ______ inactivates the microorganisms
- prevents specimen slipping in subsequent stain application and washing steps
- makes subtle alterations so that organisms more readily accepts stains
FIXING
________ an additive added to dye solution, to intensify the stain, it binds to the dye and makes it less soluble
- it increases affinity of stain for biological specimen, stain is retained better
- coats certain structures, so that it’s easier to visualize following staining.
MORDANT
_____ involves application of a single dye to a smear
- highlights entire organism; shape and basic structure’s are visible, including arrangement of cells
- are of relatively less value in diagnostic bacteriology
Simple Stain
