Development of the Cell Theory Help
Introduction to the Development of the Cell Theory
The topic of cells has been very important in biology since about the year 1665, with the studies of Robert Hooke, an English microscopist (my- KRAHS -cope-ist). Hooke used a simple microscope to view and draw the highly orderly pattern of rows and columns of hollow chambers within a thin slice of dead cork tissue. He described these hollow chambers as “little boxes” or “cells.” But even though Hooke was the first person to use the term cell, for many years no one realized the true significance of these “little boxes” within living animal and plant tissues.
Modern Cell Theory
Over 100 years later, two German scientists, Schleiden & Schwann, took a giant step forward in human thinking. Based upon repeated drawings of animal and plant cells, about 1838 they advanced the Modern Cell Theory. This theory maintains that the cell is the basic unit of all living things. Therefore, to understand the structure and function of living organisms, one must ultimately study the cell level of biological organization for a logical explanation.
Compound Light Microscope
There was a major roadblock to a good understanding of cellular anatomy and physiology, however, for another 100 years after the Modern Cell Theory was stated. The chief problem was that not enough magnifying power and clarity of the cell interior could be obtained by using a compound light microscope . In this type of microscope, several or “compound” glass lenses help focus light and magnify viewed objects. With the compound microscope, not much more than the rounded cell nucleus (“kernel”), cytoplasm, and thin cell membrane can be identified.
A critical improvement came with the introduction of the electron microscope during the 1950s. Instead of just magnifying an object a few hundred times (like the compound light microscope did), the new electron microscope focused a beam of minute electrons. With modern instruments, this produces a huge increase (up to 1000 times) in magnification. As a result, organelles and large molecules such as DNA and proteins can now be directly seen within the cell.
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