A Tour of the Cell Tour Guide… Mrs. Erin Fortenberry
Question ? Can cells be seen with the naked eye? Yes, a few are large enough, but most require the use of a microscope.
Microscope History 1590 - Janseen Brothers invent the compound microscope. 1665 - Robert Hooke “discovers” cells in cork. Early 1700’s - von Leeuwenhoek makes many observations of cells including bacteria.
Light Microscope - LM Uses visible light to illuminate the object. Relatively inexpensive type of microscope. Can examine live or dead objects.
Electron Microscopes Use beams of electrons instead of light. Invented in 1939, but not used much until after WWII.
Advantages Much higher magnifications. Magnifications of 50,000X or higher are possible. Can get down to atomic level in some cases.
Disadvantages Need a Vacuum. Specimen must stop the electrons. High cost of equipment. Specimen preparation.
Cell Biology or Cytology Cyto = cell - ology = study of
History of Cells Robert Hooke - Observed cells in cork. Coined the term "cells” in 1665.
History of Cells 1833 - Robert Brown, discovered the nucleus. 1838 - M.J. Schleiden, all plants are made of cells. 1839 - T. Schwann, all animals are made of cells.
Cell Theory All living matter is composed of one or more cells. The cell is the structural and functional unit of life.
Types of Cells Prokaryotic - lack a nucleus and other membrane bounded structures. Eukaryotic - have a nucleus and other membrane bounded structures.