Chapter 3 Observing Microorganisms Through a Microscope Flashcards
what are the main units of measure for microbes?
micrometers and nanometers
what are the conversions of unit measure for micrometers and nanometers?
How many mm are in 18 cm?
What is the difference between a simple and compound microscope?
simple microscope has 1 lens
compound microscope has 2 lenses
what is the best resolution for light microscope?
200 nanometers
what is the practical limit of resolution for the unaided eye?
20 micrometers
what is a brightfield method of microscopy?
a dark object on a bright background is viewed that can contain dyes or stains
what is a darkfield method of microscopy?
a bright object on a dark background is viewed with NO artificial color
why can a sample viewed in darkfield not be dyed or stained?
no color can be added to live cells because the chemicals in dyes/stains can kill the specimen
why might you use the method of florescence microscopy? How?
to view the presence of antigens/ antibodies
cell is stained with fluorescent dyes, antibodies get dyed and produce visible light if present
what is electron microscopy?
uses waves of electrons instead of visible light
allows for greater magnification but smaller resolution
why might we use electron microscopy? Cons?
for viewing organelles of sample (ie: golgi body/ mitochondria)
Cons: must be performed in a vacuum
distorts blurred image of cell
can only be used on dead cells
what does SEM stand for? What is its use?
Scanning electron microscopy
produces superficial image of surface structures
surface of specimen is covered in thin layer of gold
what does TEM stand for? What is its use?
transmission electron microscopy
used to view interior of cell (organelles of cells)
cell is sliced into 3 thing sections and sections are covered with heavy metals
what are differences of advantages of SEM and TEM?
SEM: magnification is up to 10,000x
resolution is down to 10 nanometers
TEM: magnification is up to 100,000x
resolution is 10 picometers
what is the definition of magnification?
Bringing an object into closer view
what is the definition of resolving power /resolution?
Ability to distinguish fine detail
what is the best magnification that we can get with a light microscope?
1000x
what type of light microscopy do we use in the lab?
compound microscope
what will a cell look like under fluorescence microscopy?
glowing green
what is used to dye in fluorescence microscopy?
fluorescent dyes called fluorochromes
