Cells
What piece of technology made the discovery of cells possible? For centuries, scientists had no idea that the human body consists of trillions of cells. What piece of technology made the discovery of cells possible? Answer: The microscope!
History In 1665 Robert Hooke made a simple microscope and looked at a piece of cork. What did he see? Small, box-shaped structures that he called “cells” because they reminded him of cells in which monks lived.
History During the late 1600’s, Dutch scientists Anton van Leeuwenhoek designed his own microscope and looked at pond water and milk. What did he see? Living organisms that they never knew were there!
History 1838 German scientist Matthias Schleiden studied plants and concluded that all plants are made of cells.
History 1839 another German scientist, Theodor Schwann reported that animal tissues are also made of cells.
History 1855 Virchow proposed that all cells are produced from the division of existing cells.
Cell Theory The observations of all of these scientists were summarized as what we know today as “Cell Theory” All living organisms are composed of one or more cells. Cells are the basic unit of structure of all living organisms. Cells come from pre-existing cells.
Microscope Technology Microscopes have enabled scientists to study cells in detail!
Compound Light Microscopes These are the microscopes we use in class. Consists of a series of glass lenses and uses light to produce an image.
Electron Microscopes Transmission Electron Microscope (TEM); Electrons are used to view an object at 500,000x Give a cross section view of the object Scanning Electron Microscope (SEM); Uses electrons to produce a 3-D image of an object.
Cells Prokaryotic Eukaryotic Cells without membrane-bound organelles No true Nucleus Smaller than Eukaryotic Ex. Bacteria Cells with membrane-bound organelles Contain a true nucleus Larger than prokaryotic Ex. Animals, Plants, Fungi, Protist
Eukaryotic vs. Prokaryotic