Cell Structure Flashcards
What is cell theory
Cell theory states that all living organisms are composed of one or more cells
What’s field of view (FOV)
The circular area visible down a microscope
What’s magnification
The number of times larger an image appears compared to the real specimen
What’s resolution
The ability to DISTINGUISH two distinct objects separately and see detail
How does magnification effect field of view
Field of view decreases as the magnification increases
How can you measure the diameter of the field of view
Using a stage micrometer
What’s a stage micrometer
A specialised microscope slide (1mm with 10 divisions)
What’s the magnification formula
image size / actual size x magnification (set up like triangle)
3 advantages of a light microscope
Cheap, easy to use, views living specimens, portable, natural colour
2 disadvantages of a light microscope
Low mag (x1500), limited res (200nm)
Name the 3 types of microscopes
Light microscope, transmission electron microscope (TEM), scanning electron microscope (SEM)
How does a light microscope work
Light passes through the specimen and is focused using the glass lenses
How does a TEM microscope work
Electrons pass through the specimen and are focused by electro magnets onto a fluorescent screen
advantages of TEM
High mag (x2000000), high res (0.1nm)
Disadvantages of TEM
Large, expensive, specialist training, black and white images, dead specimens (vacuumed)
Advantages of SEM
High mag (x2000000), high res (0.1nm but usually less, 5-20nm), can view in 3D
Disadvantages of SEM
Large, expensive, black and white images
What microscope would be most useful for viewing:
1) living daphnia in pond water
2) internal structure of mitochondrion
3) ribosomes
4) cells from a cervical smear to spot abnormalities
5) influenza virus particles
1) LM 2) TEM 3) TEM 4) LM 5) SEM
How do you prep a specimen
1) FIXATION, to preserve tissue
2) DEHYDRATION, to absorb water
3) EMBED in wax, prevents distortion
4) SECTION, thin slices
5) MOUNT, support tissue on slide
6) STAIN, makes structures visible and increases contrast