Microscopic Techniques Flashcards
What shape are bacilli?
rod
What shape is spirochetes?
spiral/ corkscrew
What shape is the coccus?
sphere
When did the microscope originiate?
17th century
How does magnifying objects work?
combining convex and concave glass lenses
who invented the telescope?
johannes kepler
what is the book diotrice about
basic principles of light refraction and magnification
who designed the first microscope?
gelileo
who coined the term microscope
giovanni faber
what did Robert Hooke do?
coined the word cell
invented compound microscope
wrote book micrographia
what did antonie van leeuwenhoek do?
perfected the creation of simple lenses and built microscopes capable of 200x
observed bacteria, protozoans, sperm, and organelles
what is aberration
distortion of an image from the ideal optical image
what is the most common aberation?
spherical aberation
how does spherical aberation occur?
light rays travel through thicker parts of the lense and are refracted to a different degree than those that travel through thinner parts
who solved the problem of spherical aberation?
Joseph lister
how did Joseph lister solve the problem of spherical aberation
placing lense at precise distances from each other
what is chromatic aberation?
failure of a lens to focus all colors to the same convergence point
how is chromatic aberration corrected?
Charles hall used a second lense of a different shape and refracting properties to realign colors with minimal impact on the magnification
what is kohler illumination
uses Condensor and diaphragm to focus light rays onto specimen
**essential to modern light microscopy
how does Kohler illumination improve the viewing of specimens
illumination and resolution are increased
who discovered the importance of light diffraction
Abbe
what do cones do?
they detect color
where are cones located?
fovea
what is magnification
the increase in the apparent size of the specimen being observed
what is resolve
ability to clearly separate two objects that are very close together
what is resolving power?
minimum distance existing between two objects when these objects can still be observed as separate entities
what is brightfield microscopy
specimens are visualized because cells differentially absorb or scatter light resulting in the differences in contrast between the objects and their surroundings
how many objective lenses does a compound microscope have?
at least three (10, 40, 100)
what is the ocular lens and the magnification
IT is the lense you look through and is 10x
what is the smallest object resolvable?
0.5 gamma per numerical aperture
how can specimens be viewed on bright field microscopy
via wet mounts, fixed and stained on glass slides to permit better examination of morphology and internal structure
what are dyes and their purpose
staining that can be used to improve the visibility
what is simple stain
utilizes one dye to improve the contrast against the unstained background
what are some examples of simple stain
methylene blue, rose bengal
what are differential stains?
use two different stains designated as the primary dye and the counterstain
what is an example fo differential stain
gram staining
what are special strains?
used to identify specific cell components such as bacterial capsules and spores
what is dark field microscopy
involve light scattering where light reaches the specimen from only the slides
what is dark field microscopy good for?
observing microbial swimming motility
what is phase contrast microscopy
uses a special condenser and a phase plate in the objective lens to amplify the variation in phase and produce the higher contrast image
what does phase contrast microscopy do?
amplify the variation in phase and produce higher contrast images
it also has better resolution than in brightfield
What is DIC microscopy
polarizer makes two distinct beams that pass through the specimen and enhances subtle differences in the cell structure
What is fluorescence microscopy
use fluorescence to reveal cells and their parts. specimen absorbs light at one wavelength and then emits light at a longer wavelength
Why do cells fluoresce
they naturally contain fluorescent substances or they have been stained
Direct Epifluorescent filter technique benefits
-target organism that can be concentrated
-remove growth inhibitors
-transferred to a different growth medium without physical injury
what is immunofluorescence microscopy used for
detecting specific proteins and uses a dye that has been covalently attached
What is FISH?
Fluorescent in situ hybridization
Confocal laser-scanning microscopy
allows to access several planes of focus in specimen
What is super-resolution imaging
shows how an individual an fluorescent protein moves within a living cell
What is an electron microscope
uses electromagnetic lense, electrons, and a fluorescent screen
what is a transmission electron microscope
clearly magnify an image 100x, electrons pass through or scatter to varying degrees
What is negative staining
background is stained
What is positive staining
the actual specimen is stained
What is scanning electron microscopy
the specimen is coated with a thin film of a heavy metal
the electron beam then scans back and forth across
