microscopy

• a light microscope uses light and different lenses to magnify objects, to allow the image to be seen through and eyepiece
• for a light microscope, the best possible magnification is around x 1000
• light microscopes use visible light and a combination of lenses to magnify images of a mounted specimen. living specimens can be viewed in their natural colour
• how do electron microscopes work?

  they use electros instead of light to produce detailed images with a high magnification.
• what are the two types of electron microscopes?

  transmission and scanning (TEM and SEM)
• Light microscopes use lenses to bend light and magnify images by a factor of roughly 100
• chemical dyes may be used to resolve specific structures with light microscopes
• electron microscopes have a much greater magnification and resolution
• what can electron microscopes be used to see?

  dead specimens in monochrome
• TEM pass electrons through specimen to generate a cross-section
• SEM scatter electrons over a surface to differentiate depth and map in 3D
• $magnification =$$image size / actual size$
• $actual size =$$image size / magnification$
• what is magnification?

  the number of times greater the image is than the specimen
• what is resolution?


  the ability to distinguish between two parts of an image. the higher the resolution, the sharper the image
• staining is used to see cell structures more clearly
• gram staining - stains gram positive bacteria red, and negative violet
• erosin - stains red blood cells and membranes pink/red
• iodine - stains starch blue/black
• methylene blue - stains nuclei and chromosomes blue