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BIO: Microscope

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Amanda S.

on 3 March 2013

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Transcript of BIO: Microscope

ELECTRON MICROSCOPE LIGHT MICROSCOPE an instrument that uses visible light and magnifying lenses to examine small objects not visible to the naked eye, or in finer detail than the naked eye allows MICROSCOPES MAGNIFICATION & RESOLUTION ENLARGEMENT ADVANTAGES & DISADVANTAGES LIGHT MICROSCOPE OIL IMMERSION: TECHNIQUES & PROCEDURES Focus with the low/medium objective lens first.

Rotate the lens and place a drop of oil directly on the objective lens and on the slide.

Slowly rotate the high powered objective lens into place and adjust the resolution as usual. A PRESENTATION BY...

- possible to observe a wide range of biological activity, such as the uptake of food, cell division and movement.

-possible to use in-vivo staining techniques to observe the uptake of colored pigments by the cells. These processes can not be observed in real time using electron microscopes, as the specimen has to be fixed, and completely dehydrated (and is therefore dead).

-low cost of optical microscopes: makes them useful in a wide range of different areas, such as education, the medical sector or for hobbyists. -Limited Magnification
The typical light microscope can only magnify images up to 400x . While electron microscopes, that can provide much greater magnifications needed to see objects like virus particles and individual atoms and molecules.

-Limited Depth Of Field
At high magnifications, light microscopes provide what are essentially 2-dimensional images of 3-dimensional objects. The result is often an unclear image of the object or organism being studied, with one clear layer showing but blurred by the surrounding layers that are out of focus. This undesirable effect occurs because of the way standard lenses have focal lengths that gather the light they focus from a 2-dimensional plane in front of the lens.

-Limited Detection of Electromagnetic Energy Spectrum ADVANTAGES DISADVANTAGES ELECTRON MICROSCOPE -extremely expensive

-Sample preparation is often much more elaborate. It is often necessary to coat the specimen with a very thin layer of metal (such as gold). The metal is able to reflect the electrons.

-sample must be completely dry (impossible to observe living specimens)

-not possible to observe moving specimens (they are dead).

-not possible to observe color. Electrons do not possess a color. The image is only black/white. Sometimes the image is colored artificially to give a better visual impression.

-require more training and experience in identifying artifacts that may have been introduced during the sample preparation process.

-high energy of the electron beam, sample is exposed to high radiation, therefore not able to live.

-high space requirements (may need a whole room)

-high cost of maintainance DISADVANTAGES STRUCTURE APPLICATION STRUCTURE APPLICATION It is a type of microscope that uses an electron beam to illuminate a specimen and produce a magnified image. The electrons have wavelengths about 100,000 times shorter than visible light photons, hence structures of smaller objects can be seen. Uses electrostatic and electromagnetic lenses to control the electron beam and focus it to form an image. Semiconductor and data storage:
Defect and failure analysis

Biology & Life Sciences:
Pharmaceutical QC


High-resolution imaging Medical field:
Smear test

Pharmaceutical researches SHARPNESS Resolving power of EM > LM (Optical microscope) EM can achieve better than 50pm resolution and magnifications of up to about 10,000,000x. Modern EM produces electron micrograph.

Specimens used are non-living, dehydrated, relatively thin or small. 40x 5mm
100x 2mm
400x 0.45mm
1,000x 0.18mm AMOUNT OF DETAIL 20x 40x 100x 200x 60x MV: Resolution
CV: Magnification MV: Magnification
CV: Resolution ORGANELLES UNDER LIGHT MICROSCOPE can be seen Plasma membrane
Cell wall

Mitochondria requires electron microscope Ribosomes
Golgi Apparatus
Smooth & Rough ER requires staining: cannot be seen thank you ! -powerful magnification.

-many technological and industrial applications: semiconductor inspection, computer chip manufacturing, quality control, as part of a production line.

-Transmission electron microscope (TEM) used to see 2D images of thin sections of a specimen

-Scanning electron microscope (SEM) can give 3D images

-At lower energy levels: can resolve much smaller structures.

-At high energy levels: elections cause the subject they strike to florescence X-Rays, can be used to identify the elements in the subject. ADVANTAGES
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