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Exploring the Evolution of Microscopes and the Cell Theory

This lesson explores the history and development of microscopes from early models to modern variations. It covers key figures like Zacharias Janssen, who created the first compound microscope, and Antonie van Leeuwenhoek, known for his simple microscope, which achieved significant magnification. The lesson examines various types of microscopes, including simple, compound, stereomicroscopes, and electron microscopes, explaining magnification and image clarity. Additionally, it outlines the foundational cell theory, highlighting the role of cells in all living organisms.

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Exploring the Evolution of Microscopes and the Cell Theory

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  1. LESSON 3 Ch. 2 “Cells”Section 2: “Viewing Cells” Pages 47 - 51

  2. EARLY MICROSCOPES • Zacharias Janssen - made 1st compound microscope • a Dutch maker of reading glasses (late 1500’s)

  3. Leeuwenhoek • made a simple microscope (mid 1600’s) • magnified 270X • Early microscope lenses made images larger but the image was not clear

  4. Leeuwenhoek's microscope A) a screw for adjusting the height of the object being examined B) a metal plate serving as the body C) a skewer to impale the object and rotate it D) the lens itself, which was spherical

  5. MODERN MICROSCOPES • A microscope is simple or compound depending on how many lenses it contains • A lens makes an enlarged image & directs light towards you eye

  6. A simple microscope has one lens • Similar to a magnifying glass • Magnificationis the change in apparent size produced by a microscope

  7. COMPOUND MICROSCOPE • A compound microscope has multiple lenses • (eyepiece & objective lenses)

  8. STEREOMICROSCOPE • creates a 3D image

  9. TOTAL MAGNIFICATION • Powers of theeyepiece (10X) multiplied by objective lenses determine total magnification.

  10. ELECTRON MICROSCOPES • More powerful; some can magnify up to 1,000,000X • Use a magnetic field in a vacuum to bend beams of electrons • Images must be photographed or produced electronically

  11. ScanningElectron Microscope (SEM) Electron microscope image of a spider Electron microscope image of a fly foot • produces realistic 3D image • only the surface of specimen can be observed

  12. TransmissionElectron Microscope (TEM) • produces 2D image of thinly sliced specimen • detailed cell parts (only inside a cell) can be observed

  13. ScanningTunneling Microscope (STM) • able to show arrangement of atoms

  14. CELL THEORY • A theory resulting from many scientists’ observations & conclusions

  15. CELL THEORY1. The basic unit of life is thecell. (Hooke) • In 1665, an English scientist named Robert Hooke made an improved microscope and viewed thin slices of cork viewing plant cell walls • Hooke named what he saw "cells"

  16. CELL THEORY2. All living things are made of1 or more cells. • Matthias Schleiden(botanist studying plants) • Theodore Schwann(zoologist studying animals) stated that all living things were made of cells Schwann Schleiden

  17. CELL THEORY3. All cells divide & come from oldcells. (Virchow) Virchow

  18. This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.

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