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What is a key characteristic of the Transmission Electron Microscope (TEM)?
Which statement is true about Scanning Electron Microscopy (SEM)?
What does 'electron lucent' refer to in the context of TEM imaging?
How does the imaging process of electron microscopes differ from light microscopes?
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What is the resolution power of a Transmission Electron Microscope (TEM)?
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Which of the following best describes resolution in microscopy?
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What is the primary purpose of a microscope in histology?
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Which of the following sequences accurately represents the metric conversions detailed in histology?
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What is the function of the condenser in a light microscope?
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Which of the following lenses is responsible for the initial magnification in a light microscope?
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Which type of microscope uses a beam of electrons for visualization?
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When carrying a microscope, how should it be supported?
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In a light microscope, what role does the ocular lens play?
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What is the total magnification when using a 10x ocular lens with a low power objective lens?
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Which type of microscope is best suited for studying unstained, living cultured cells?
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What is the primary use of a polarizing microscope?
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Which type of microscopy utilizes laser light to achieve high resolution and sharp images?
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Why is an electron microscope more powerful than a light microscope?
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What is the total magnification when using a 100x objective lens with a 10x ocular lens?
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What is the limitation of the eyepiece lens in microscopes?
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Which microscope is primarily used for observing very small objects that cannot be seen by light microscopes?
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Study Notes
Electron Microscopy
- There are two main types of electron microscopes: Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM)
- TEM has a resolution power of around 0.2nm and a magnification power of up to 400,000 times.
- TEM uses a beam of electrons focused by electromagnetic lenses to create an image.
- TEM images appear as shades of black and white, with electron-dense areas appearing black and electron-lucent areas appearing white.
- Electron-lucent areas allow electrons to pass through easily, while electron-dense areas absorb or deflect electrons
- TEM uses ultrathin tissue sections (40-90nm)
- To view a TEM image, a fluorescent screen is needed to convert the energy of electrons into light
- SEM uses a beam of electrons to scan the surface of a specimen coated with a heavy metal (gold)
- The reflected electrons are collected by a detector to create a 3D black and white image on a TV screen.
- SEM only shows the surface of a specimen because the electron beam does not pass through it.
Light Microscopy
- Microscopes are used to view specimens too small to be seen with the naked eye.
- Magnification refers to the degree of enlargement, and resolution refers to the ability to show details clearly.
- The most important units of measurement in histology are:
- centimeter (cm): 10 millimeters (mm)
- millimeter (mm): 1000 micrometers (µm)
- micrometer (μm): 1000 nanometers (nm)
- nanometer (nm): 10 Angstroms (Ao)
- Light microscopes use light to illuminate the specimen.
- Electron microscopes use a beam of electrons to illuminate the specimen.
- Brightfield microscopy, phase contrast microscopy, fluorescence microscopy, polarizing microscopy, and confocal microscopy are all types of light microscopy
- TEM and SEM are types of electron microscopy.
Components of a Light Microscope
- The frame consists of the base, arm, and stage.
- The magnifying system consists of the lenses.
- The illumination system provides the light source, which can be a mirror to reflect daylight or an electric lamp.
- The condenser is located under the stage and collects and focuses a cone of light to illuminate the tissue slide.
- The objective lens enlarges and projects the illuminated image of the object in the direction of the ocular lens.
- The ocular lens (eyepiece) further magnifies the image projected by the objective lens and projects it onto the viewer's eye.
Microscope Magnification
- To calculate the total magnification of a microscope: multiply the magnification of the ocular lens by the magnification of the objective lens.
- The objective lenses provide higher magnification and resolving power than the ocular lens.
- The ocular lens only enlarges the image already obtained by the objective lens, it does not improve resolution.
- The total magnification of a light microscope depends on the objective lens used.
Special Types of Light Microscopes
- Phase contrast and interference microscopes allow the study of unstained cells, which are transparent and colorless.
- Fluorescence microscopes use fluorescent dyes to visualize specific structures or molecules.
- Polarizing microscopes are used to study crystals and substances with repeating molecular arrangements, such as collagen, microtubules, and microfilaments.
- Confocal microscopes use a laser to create high-resolution, sharp, 3D images.
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Description
Explore the fundamentals of electron microscopy, focusing on the two primary types: Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM). Understand their operational mechanisms, resolution capabilities, and the imaging techniques involved in observing specimens. This quiz will enhance your knowledge of electron microscopy applications and imaging results.
