microscopy Flashcards
who put together one of the first working optical microscopes
robert hooke
state what cell theory means
that cells are fundamental unit of structure function and organisation of all organisms.
light microscope
main tool for observing cells.
electron microscope
gives mag of over 50000 times
total magnification equation
magnification of objective lens * magnification of eyepiece lens
equation for image size
actual size times mag
why is staining used
so different parts of the cell may be seen and different types of cells
haematoxylin stain
stains the nuclei of plant and animal cells purple blue or brown
methylene stain
staisn nuclei of animal cells blue
acetocarmine stain
staisn chromosomes in dividing nuclei in both plant and animal cells
advantages of light microscopes
-can see living plants or parts of them directly. compare prepared slides with living tissue
-cheap so available to everyone
-light and portable so can be used anywhere
disadvantages of light microscopes
-preservation of living tissue produce atrefacts that disrupt the image seen
-limited powers of resolution and magnification
how do electron microscopes work
use beams of electrons to see an image. electrons behave like light waves with tiny wavelength and electrostatic lens focuses beams to form an image.
transmission electron micrographs
two d images like those from light microscopes
scanning electron micrographs
lower mag but 3 d .
ass false colours but added after taking picture
