Discovery of Cells and the Development of
•The study of cells started about 330 years ago.
oBefore that time cells escaped notice because of
their small size.
oWith the invention of the microscope, cells became
visible and many new discoveries were made
oEven today the study of cells reveals more detail,
and its secrets, which are in fact the secrets of life
Early Pioneers of Cell Biology
•1665: English Scientist and Microscopist
Robert Hooke described a honeycomb-like
network of cellulae (Latin for little storage
rooms) in cork
•Antonie van Leeuwenhoek (16321723) described cells in a drop of pond water
using a microscope.
oFirst person to observe bacteria and protozoa.
oSome of his lenses could magnify objects 250X.
The cell is the basic unit of
•1838: Matthias Jakob Schleiden, a German
botanist, concluded that all plant tissues are
composed of cells and that an embryonic plant
arose from a single cell.
Theodor Schwann, a German
biologist, reached the same conclusion as
Schleiden about animal tissue being
composed of cells.
Cork Cells viewed with a
compound light microscope @
Scanning electron micrograph of
•1. Is the cell wall living or dead?
•2. Describe three ways that a plant cell differs
from an animal cell.
•3. List 3 structures that are associated with
both prokaryotic and eukaryotic cells.
•Why do we stain specimens?
•Why must the specimen you observe be very
Cell Lab Directions
•1. Make labeled drawings of the cork cells,
onion cells, and your cheek cells at 400x.
oFor the cork cells label the cell walls and lumen
(space inside the cell wall of each cell).
oFor the onion cells label the cell wall, cytoplasm,
and central vacuole. If you observe and draw a
nucleus label that too.
oFor the cheek cells label the cell membrane,
cytoplasm and nucleus.
•Make all drawings at least ¼ the size of the
page. The title and magnification used for the
drawing goes below the drawing.