Crash Course Biology: Microscopy

Introduction

• Antoni von Leeuwenhoek discovered bacteria in 1683 by examining plaque from his teeth using a homemade microscope.
• He named the organisms "animocules," the first observation of bacteria.
• Today's microscopes are more powerful and accessible.

Significance of Microscopes

• Microscopes allow us to observe the microscopic scale where many biological processes occur.
• Offers insights into cells, proteins, and molecules.

Techniques to Explore Microscopic World

• Chromatography: Separates chemical compounds.
• Mass Spectrometry: Identifies molecules by weight.
• Spectroscopy: Identifies molecules based on light absorption.

Types of Microscopes

1. Light Microscope (Optical Microscope)

• Dates back to the 1600s.
• Works by bending light to magnify the specimen.
• Can magnify up to 2,000 times.
• Limitations in resolution at high magnifications.

2. Electron Microscope

• Invented in the 1930s.
• Uses beams of electrons instead of light.
• Allows viewing of very small specimens with higher resolution.
• Can magnify up to 100,000 times.
• Specimen preparation can kill cells.

3. Scanning Probe Microscope

• Invented in the 1980s.
• Uses sharp probes instead of light/electrons.
• Produces detailed images up to 100 million times the specimen's size.

Microscopy Techniques

• Fluorescence Microscopy: Uses dyes and specific light wavelengths to view living cells and their interactions.
• Cryo-Electron Microscopy: Freezes samples to capture detailed images and create 3D models.

Practical Tips for Using a Microscope

• Start low: Begin with the lowest magnification lens.
• Center and focus: Ensure the specimen is centered and focused.
• Fine adjustments only: At highest magnifications, use fine adjustments to avoid damaging lenses or specimens.

Conclusion

• Microscopes are essential tools in biology, providing insights into the microcosmos.
• With advancements, they are more accessible, enabling community science.
• Future episodes will explore cells and how microscopes enhance our understanding of life's building blocks.

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Additional Resources:

• Visit biointeractive.org/crashcourse for classroom resources.
• Support Crash Course through Patreon.