Cell structure

• Allow to dry • Heat it by a Bunsen burner

To allow light to pass through easily

Stains cell walls purple, used in gram staining

Stains nucleus of animal cells to give contrast

Negative stain that is not taking by the cell but provides a contrast between the cell and the background

Solid specimens, thin slices called sectioning, coverslip on top

Wet specimens, suspended in water or oil, coverslip placed on an angle

soft specimens, wet mount squashed between the slide and coverslip

the edge of the slide is used to smear the sample creating an even coat

eyepiece graticule

1 graticule division = number of micrometers ÷ number of graticule division

graticule divisions x magnification factor = measurement (µm)

Resolution is the ability to distinguish between two separate points

Limit of resolution is about one half of the wavelength of the radiation used to view the specimen

Magnification is how many times bigger the image of a specimen observed is in compared to the actual (real-life) size of the specimen

• A series of (usually 3) objective lenses, each with a different magnification • An eyepiece lens, which often has a magnification of x10

uses beams of electrons that pass through the specimen before being viewed. Only those transmitted are seen. It allows us to see thin sections of specimens (inside the cell).

an electron beam is used to scan the surfaces of structures and only the reflected beam is observed.

Shine light through specimens, this light is passed through the objective lens (changeable) and then through the eyepiece lens (x10)

0.5 nm

200 nm

Electron microscope, because if there was air the electrons would scatter all around