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Questions and Answers
What is the primary function of a microscope?
What determines the quality of a microscope?
What is the minimum distance that two points can be separated and still be distinguished as two separate points?
What is the advantage of using an electron microscope over a light microscope?
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What is the purpose of a dissecting microscope?
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What is the minimum size that a light microscope can resolve?
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What is required for electron microscopy to be performed?
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What is the unit of measurement for the size of an object viewed under a microscope?
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What is a key difference between preparing cells for a light microscope and an electron microscope?
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What is the purpose of staining specimens with heavy metal salts in transmission electron microscopy?
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What type of electron microscope is used to show the internal structure of cells?
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What is the purpose of coating a specimen with a thin layer of gold metal atoms in scanning electron microscopy?
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What is a common goal of scientists when using electron microscopes?
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What type of electron microscope is used to produce images of the surface features of cells and organisms?
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Study Notes
Microscopy in Cell Biology
- Microscopy has played a crucial role in the development of the cell theory and continues to aid scientists in understanding cell structure and function.
- Microscopes work by magnifying objects, with quality measured in terms of magnification and resolution.
Magnification and Resolution
- Magnification allows objects to appear larger.
- Resolution is the minimum distance between two points that can be distinguished as separate points.
Light Microscopes
- Light microscopes allow us to see cells and some of their contents, which cannot be seen with the naked eye.
- Light travels through the specimen, then through lenses to the eye or computer screen.
- The object appears magnified due to bending of light by lenses in the microscope.
- The light microscope can only resolve objects down to 0.2 micrometers in size.
- A micrometer (µm) is 1/1000th of a millimeter.
Types of Light Microscopes
- The compound light microscope is the most common type.
- Dissecting microscopes (stereo microscopes) are used to view whole organisms or the external structure of organisms.
- Dissecting microscopes have lower magnification and resolution than compound light microscopes.
Electron Microscopes
- Electron microscopes allow us to see cells and their contents with high magnification and greater resolution than light microscopes.
- The image from an electron microscope can be produced on a computer screen or photographic plate.
- Cells must be prepared for electron microscopy by being fixed, dehydrated, stained, and embedded in plastic resin.
Types of Electron Microscopes
- Transmission electron microscopes (TEM) require very thin specimens stained with heavy metals.
- TEM is used to show the internal structure of cells, known as "fine structure".
- Scanning electron microscopes (SEM) produce images of the surface features of cells and organisms.
- SEM uses a thin layer of gold metal atoms to create an image on a screen.
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Description
Understand the basics of microscopy, its importance in cell theory, and how it aids in studying cell structure and function. Learn how microscopes work and the key factors that affect their quality.
