Just as an organism is dependent upon its internal organs
to carry out life's processes, each of the trillions of cells found inside an organism is dependent upon its internal organelles for its survival. If you were asked to make a list of vital organs contained within your body, your list would probably include your heart, brain, lungs, liver, and kidneys. And there are many other organs within you. Similarly, each cell contains many organelles and in this exercise, we will emphasize selected ones that exemplify the division of the labor of life's processes occurring in cells.
The cell's nucleus was discovered by the Scottish
botanist, Rober Brown (1773-1858) in 1831. The word nucleus was from
the latin for "little nut." But even with the 1839 statement of cell
theory, further discoveries into the true nature of cell structure were very
slow. This is because living cells are almost completely transparent. The staining
of cells with dyes to reveal their inner structure is actually due to the 1856
research of an Englishman named William Perkin who was trying to produce, in
his home laboratory, the antimalarial compound, quinine. Although failing to
make quinine, he did succeed in synthesizing a purple compound that was found
to be an excellent dye for silk. This marked the beginning of the age of synthetic,
organic chemicals to be used for every conceivable human use. And one of those
uses was application of the dyes to living cells to see what would happen. Such
application resulted in cells having many of their inner structures revealed.
Walther Flemming (1843-1905), a German anatomist applied aniline dyes to cells
and noticed a deep staining substance in the nucleus which he called chromatin
(from the Greek word for color). Further work resulted in the identification
and naming of chromosomes and their movements during cell division (called mitosis).
It is of interest that Flemming did not see the
genetic significance of the mitotic process he had discovered. Although Gregor
Mendel had already completed and published his basic genetic work, Flemming
was unaware of it. Twenty years later a Dutch botanist, Hugo De Vries (1884-1935)
rediscovered Mendel's work. And there was a blossoming of Flemming's work in
that it provided the physical basis for the movement of genes that Mendel had
worked out in his experiemtns with garden peas.
Further significant advances in the study of cellular
organelles had to wait until the late 1940's when cells were first observed
with the electron microscope. Not relying on glass lenses with their various
aberrations in relation to the passage of light through them, and not relying
on light itself with its intrinsic shortcomings for ultimate magnifying power,
beams of electrons, with their extremely short wavelengths, could be aimed at
extremely thin sliced, and appropriately, chemically treated, slices of material.
The resulting magnifications of 50,000 to 200,000X resulted in a revolution
in cell biology. Organelles were finally seen in stunning, revealing close-ups,
and many new organelles were discovered.