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Questions and Answers
Who observed a thin slice of cork through a microscope in 1665?
What is cell theory?
All living things are composed of cells.
What did Antonie van Leeuwenhoek call the microorganisms he observed?
Animalcules
What type of microscope did Anton van Leeuwenhoek use?
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The resolving power of a Transmission Electron Microscope (TEM) is about ______ nanometers.
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How do you calculate total magnification in a compound light microscope?
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What is the total magnification of a compound light microscope with an objective lens magnification of 40X and an ocular lens of 10X?
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What are the two types of electron microscopy mentioned?
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What is the primary advantage of using electron microscopes compared to light microscopes?
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Match the type of microscopy with its description:
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Study Notes
Discovery of Cells
- Robert Hooke's observations in 1665 led to the identification of "cells" in cork, marking a foundational development in cell biology.
- Anton van Leeuwenhoek (1673-1723) enhanced microscopy and was the first to observe live microorganisms, coining the term "animalcules."
- Leeuwenhoek's microscopes used biconvex lenses, achieving magnifications of approximately 270 times with a resolution of about 1.35 μm.
Microscopy Techniques
- Light microscopy utilizes visible light to observe specimens, with several types classified as:
- Compound Light Microscope (LM)
- Bright-field
- Phase-contrast
- Differential interference contrast
- Dark-field
- Fluorescence
- Resolution refers to the ability of lenses to distinguish fine detail, enabling the identification of closely positioned points.
Total Magnification Calculation
- Total magnification of a specimen is calculated by multiplying the magnification of the objective lens by that of the ocular lens.
- Common objective lenses have magnifications of 10X (low power), 40X (high power), and 100X (oil immersion), while ocular lenses typically magnify by a factor of 10.
Electron Microscopy
- Electron microscopes use electrons rather than visible light for imaging, consisting of transmission and scanning types.
- Transmission Electron Microscopy (TEM):
- Provides high magnification and resolution, capable of viewing structures at the molecular level.
- Requires thin sections of specimens that are stabilized and stained for visibility, with resolving power around 0.2 nanometers.
- Scanning Electron Microscopy (SEM):
- Specimens are coated with a thin metal film (e.g., gold) for observation, effective for larger samples.
- Offers excellent depth of field, making it ideal for detailed imaging of surfaces.
Conclusion
- Microscopy advancements, from Hooke’s simple microscope to modern electron microscopes, have significantly enhanced the understanding of cellular structures and functions.
- Key figures in early microscopy laid the groundwork for the development of cell theory, emphasizing that all living organisms are composed of cells.
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Description
Explore the fundamental discoveries in cell and molecular biology. This quiz covers historical advancements, including the invention of the microscope by Robert Hooke and Antonie van Leeuwenhoek. Test your knowledge on the structure and function of cells.
