Lecture 2-microscopes Flashcards
what did cell discovery wait on
the invention of microscopes
what is a microscope
the techinical field of using lenses to magnify things that cant be seen by the naked eye
when did scientest descover ways of observing cells
since the late 1600s
what did robert hookes name and when
in the late 1600s he named cellulae
what did anton van leeuwenhoek observe
he observed animalcules and describes protists and sperm cells
what did robert brown do and when
in the 1820s he called nucleus to discrete circled body in cells
what are the 3 basic components of a microscope
optical, mechanical, source of illuminaltion
what are the 3 types of microscopes
optical
electron
florecent
what is resolution
the ability of a microscope to distinguish two objects as being separate
when you have higher magnification what does this do to the resolution
higher magnifacations increases resolution
what does contrast do
it helps with detail but cant increase resolution
what microscope will we use in the lab
bright field
what does phase contrast do
it creates slight phase shifts in the illumination light, which manifest as higher detailed images
what are contrast enhancing methods
phase contrast
dark field microscopy
differential interference contrast (DIC)
what is dark field microscopy
illuminates sample at an angle so light does not hit lends directly
only light thats is scattered upwards by the sample reaches the objective lens
what is differential interference contrast (DIC)
it is simular to phase contrast. it uses prisms to generate interference patterns for contrast and gives a pseudo-3D apearence
what is confocal fluorescence microscopy
it increases contrast by capturing very thin slices of a specimen and provides a sharper 3D image
how does a confocal fluorescence microscopy capture shaper 3D images
it does this by passing the emitted light through a tiny pin hole, which removes out of focus light
what are the two types of electron microscopes
transmission microscope (TEM)
scanning electron microscope (SEM)
how do electron microscopes work
a beam of electrons is focused on a thin specimen in a vacuum
electrons that pass through from the image; structures that appear darker.
in an electron microscope how can you highlight areas of interest
by using various staining and fixing methods
what is transmission electron microscopy (TEM) mostly used for
its primarly used to examine structures within the cell
