Sample: Microscopy

MICROSCOPY

Exam questions on this section commonly require you to:

• Compare and contrast how the 2 microscopes work
• Comment on the limitations of the 2 microscopes
• Distinguish between the appearance of cells under the light microscope and electron microscope
• Describe an experiment in which you used light microscopy to view cells – both stained and unstained.

There are two types of microscope used to view cells:

1. Light Microscope
2. Electron Microscope

LIGHT MICROSCOPE

• Uses a beam of light to view specimen
• Uses glass lenses for magnification
• Average light microscope magnification – 400 times
• Eyepiece lens – magnifies image
• Coarse adjustment wheel – allows for rough focusing
• Objective lens – Magnifies Image
• Nosepiece – Revolves different objective lenses
• Stage/clip – revolves around different objective lenses
• Mirror/ light source – Supply light
• Diaphragm/ iris – Allows light intensities to illuminate the image

Typical Animal Cell Under Light Microscope

Animal Cell

Typical Plant Cell Under Light Microscope

ELECTRON MICROSCOPE

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• Uses beam of electrons to view specimen
• Uses magnets for magnification
• Cannot view living specimens – due to the staining and embedding of magnets
• Very high magnification- greater than 500,000 times

 

Animal Cell Under Electron Microscope

Plant Cell under Electron Microscope