Science Focus Topic 2 Notes: Microscopes and Cells | Print |
A World Too Small To See ?

- when an object is made to appear larger than it?s actual size, it is said to be magnified.

Early Microscopes ?

- micro-organisms were first discovered by Anton van Leeuwenhoek.  His hobby of grinding lenses led him to eventually make the first  simple microscope to study blood samples, pond water and plaque (which he scraped from his teeth)  The organisms he found ? that were single cells ? he called ?animalcules?

  Robert Hooke was also experimenting with microscopes he had built to look at different things, such as a tiny piece of cork.  The small holes that were honeycombed were described as ?little rooms or boxes? and the word cellulae was used to name them (Latin form of ?cell?).

Cells in All Living Things ?

-   Two scientists (Matthias Schleiden and Theodore Schwann) who studied cells combined their observations to make a hypothesis ? all living things are made up of cells.
-   A cell is the basic unit of life, because all the functions carried out by living things are carried out by their individual cells
-   Rudolf Virchow contributed his observation and together the Cell Theory was formulated:

all living things are composed of one or more cells
cells are the basic units of structure and function in all organisms
(Web: )

Microscopes Today ?

- Technology improvements have lead to the development of compound light microscopes (2000X magnification) and electron microscopes (2,000,000X magnification).
- there are two types of electron microscopes:
          TEM (transmission electron microscope) and
          SEM (scanning electron microscope)

- The microscope has become a valuable tool for the
investigation of the microscopic world  

See the electron microscopic images on page 114

Compound Microscope

Topic 2 Review p. 114