1.1 The Microscope in Cell Studies Flashcards
Make temporary preparations of cellular material suitable for viewing with a light microscope.
Materials needed (5)
Cover slip
microscope slide
pipette
stain
blotting paper
Drawing cells from microscope
rules: (4)
Draw only few representative cells
draw the cell wall (if plant cell)
Do not draw the nucleus as a solid blob –> add nucleolus if seen
Calculating magnifications or actual size or image size formula
I= AM
Transmission electron microscope (how they work) (4)
beam of electrons is passed through the specimen before being viewed. Only the electrons that are transmitted (pass through the specimen) are seen.
–> see inside the cell
Scanning electron microscope (2)
Th electron beam is used to scan the surfaces of structures
reflected beam is observed
TEM vs SEM
SEM –>
+ you can see 3D
TEM –>
+ higher resolution
SEM resolution between 3nm and 20 nm
1 mm = ___ um = ___ nm
1000
1,000,000
Define resolution
measure of the microscope’s ability to distinguish between two points which are close together on an object
Define magnification
the number of times greater that an image is than the actual object
light microscope max magnification
x1500
light microscope limit of resolution
200nm
electron microscope max magnification
x500,000
electron microscope limit of resolution
0.2 nm
a student calibrated an eyepiece graticule using a stage micrometer
- each division of the stage micrometer was 0.01 mm
- with a x10 magnification objective lens, 10 eyepiece graticule units matched 10 divisions on the stage micrometer
The same microscope was used with a x40 instead of a x10, magnification objective lens to measure the diameter of an alveolus. The diameter of the alveolus was found to be 96 eyepiece graticule units.
The eyepiece lens was not changed.
What is the best estimate for the diameter of the alveolus.
(wrong test answer)
240 um
Which type of microscope has better resolution?
Electron microscopes, because the wavelength of an electron is shorter than the wavelength of light
