Cell : Cell Discovery

Antoine Van Leeuwenhoek

·        A Dutch cloth merchant, was the first to see individual cells and recognize them as living units, but he did not call them cells.

·        He also discovered that a drop of pond water was teeming with tiny moving creatures animalcules.  These animalcules are known today as protozoans, which include the Paramecium and Euglena that we commonly see in a drop of hay infusion.

·        He also observed the sperm cells in semen, the red cell in blood, and bacteria in feces and tartar.

Robert Hooke

·        An English scientist, who coined the name “cell”.

·        In 1665, Hooke wondered why cork floats easily on water.  His curiosity drove him to find the reason for his observation.  He sliced the cork into thin pieces from the bark of an oak tree and studied them under his microscope.  He saw tiny pores or compartments glued together, which reminded him an empty rooms monks inhabit in a monastery.

·        He called them cells, from the Latin word cellulae which mean “small room”.

·        Hooke most important contribution in Biology:

o       Book of Micrographia – which details his microscopic observation.

o       He described the tiniest components of living plant tissue.

o       He demonstrated the observations of different organisms like sponges, lice, fleas and bird feathers.

o       Confirmed Leeuwenhoek’s discovery of animalcules.

Years later, the development of better microscopes revealed that the cell contains a living component inside the cell wall.  This called protoplasm, which means, first formed substance.

Soon after, microscopists were able to distinguish two different regions of the protoplasm, the viscous central core or nucleus, and the surrounding cytoplasm.

With the invention of the electron microscope, the cell organelles (tiny organs within the cell that perform specific functions) were discovered.

Theory of Cell 

All living things are composed of cells and that these cells can reproduce themselves.

·        1838, Matthias Jakob Schleiden, a German botanist stated that all plants are made up of cells.

·        A year later, Theodore Schwann, a German zoologist, published the idea that all animals are made up of cells.

·        Fifteen years later, Rudolph Virchow, a German physician, hypothesized that cells do not form on their own, but rather, come from other cells that divide.

The ideas of these 3 and other scientists were put together to form the theory of cell.

1.      All living things are made up of one or more cells.

2.      Cells are the basic living units within organisms.  The chemical reactions of life take place within the cells.

3.      All cells arise from pre-existing cells through the process of cell division.

Description of Cell

Meaning of cell?

Cells are the basic units of structure and function in organisms.

–The cell is a dynamic “machine”.

–It operates 24 hours a day.

–It is able to carry out its functions with the help of its “spare parts.”

·        An adult human body contains about 60 trillion cells while a newborn baby contains 2 trillion cells.

·        Bacteria are the smallest cells, about 1 to 10 micrometers thick.

·        An average human cell is 10 times larger than a bacterial cell.

·        A few cells like the large fish eggs, and yolk are visible to the naked eyes.

·        Cells vary in shape. 

·        The skin cell is sheet-like because its primary function is to cover the body.

·        The xylem cells of plants are long and tubular because they transport water throughout the plant.

A Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms.

An Animal cells are eukaryotic cell that makes up many tissues in animals. The animal cell is distinct from other eukaryotes, most notably plant cells, as they lack cell walls and chloroplasts, and they have smaller vacuoles. Due to the lack of a rigid cell wall, animal cells can adopt a variety of shapes, and a phagocytic cell can even engulf other structures.

Cell must obtain food and water and eliminate excessions, metabolic waste products, and other materials in order to keep themselves in equilibrium with their external environment.  This state of equilibrium is called homeostasis, homo means same; stasis means standing.  Homeostasis must be achieved in order for the cell to survive and build new parts.  The exchange of materials between the cell and the environment is due to two major process: passive and active transport.

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Tags: animal cell, cell, cell discovery, cell organelles, discovery of cell, major process in cell and environment, parts of cell, plant cell, theory of cell, what is cell

Category: Biology