microscopes topic
- Created by: kierasanghera
- Created on: 20-05-16 21:52
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- Microscopes topic
- eukaryotic cells
- cells containing a true nucleus as a linear DNA existing as chromosomes
- prokaryotic cells
- cells that lack a true nucleus- circular strand in the cytoplasm
- light microscopes
- uses glass lenses to refract light waves to produce a magnified image of the object
- specimen used needs to be thin and transparent to allow light waves to pass
- works by:focusing light onto specimen using condenser lens,light passes through specimen
- light then captured and refracted by the objective lens
- light waves travel up to the eye piece lens creating the final image
- light then captured and refracted by the objective lens
- staining: used to bind to parts of the specimen and not others,giving contrast between different parts of the specimen,allowing structures to be seen more easily
- uses glass lenses to refract light waves to produce a magnified image of the object
- magnification
- image size/real size
- resolution is theability to distinguish between two objects that are close together
- electron microscopes
- use beams of electrons (shorter than light waves) which means it gives a higher resolution (0,5nm)
- series of electromagnets focus electrons onto specimen
- where electrons hit the screen is bright, where they don't is dark
- black and white image formed
- where electrons hit the screen is bright, where they don't is dark
- transmission electron microscope
- specimen stained with heavy metal salts
- where the stain is not taken up the electrons will pass through,giving contrast
- 2D image formed, max mag 500,000x, resolution- 0,5nm
- where the stain is not taken up the electrons will pass through,giving contrast
- specimen stained with heavy metal salts
- scanning electron microscope
- bounces electron beams off surface of the specimen
- gives a 3D surface image with max mag:300,000x and resolution:0,2nm
- bounces electron beams off surface of the specimen
- eukaryotic cells
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