2.1 Observing Cells Flashcards
What is cell theory?
cells are a fundamental unit of structure, function and organisation in all living organisms
Explain why stains are used when preparing tissue for examination using a
light microscope
provides greater contrast
the stain is taken up by specific parts of the cell
What are light mircroscopes used for
Study living cells and everyday use
What are electron microscopes used for
They are used for higher magnification and provide higher resolution images
What are some advantages to the light microscope
Can see living plants and animals or parts of them
Cheap and available in school
Portable
What are some cons to light microscopes
Limited magnifciation
Limited resolution
How does a electron microscope work
It uses a beam of electrons to form an image, the electrons are scatterd by the specimen
How does an image form in a EM
The electrons behave like light waves with a very tiny wavelength. An electromagnetic lens focuses the electrons beam to form an image
What does resolving power do in EM
the RP increases as the wavelength gets smaller so the electron microscope can resolve MORE detail
What has to be done for a EM to work
the specimens have to be in a vacuum
Why are specimens in a EM microscope stained with lead or uranium
to improve the scattering of the electrons and make greater contrast in the image making it clear.
What are advantages of using EM
Huge powers of magnification and resolution
What are some disadvanatges to EM
Expensive
sample must be placed in a vaccum ,so you can magnify living things
Produces black and white images
What is magnification
a measure of how much bigger the image you see us than the real object
what is the importance of staining specmens in micropscopy
provides contrast between the organelles and the cytoplasm allowing strucutres to observed
