Discovering Cells Pages 50-57

1. Discovering CellsPages 50-57

2. Cells are the basic unit of structure and function in all living things. • All living things are made of cells • All life processes happen in cells • Getting oxygen, getting rid of waste, obtaining food, growing, etc. • Cells are small, can’t be seen with the eye.

3. First Observations of Cells • 1590-The invention of the microscope by Hans Janssen. • This invention makes it possible for people to discover and learn about cells • In class we use a COMPOUND LIGHT MICROSCOPE – this is a scope with more than one lens that uses light to focus

4. Robert Hooke • English scientist and inventor • One of the first people to observe cells • 1663 he observed the cells of a slice of cork through a compound microscope he built himself • Hooke called them cells because they reminded him of tiny rectangular rooms

5. Anton van Leeuwenhoek • Amateur scientist who made his own lenses and constructed simple microscopes • First person to spot tiny single-celled organisms that we call bacteria. He first noticed these organisms on teeth scrapings. • Called them animacules.

6. Once cells were seen, the cell theory was developed. • Shleiden and Schwann’s observations that all plants were made of cells and all animals were made of cells led to: “All living things are made of cells.” • Virchow proposed that new cells are formed ONLY from cells that already exist. This led to: “All cells come from cells.” • As more cells were viewed using microscopes, it became believed that: “Cells are the basic unit of structure and function in all living things.”

7. Advancements in Microscopy • Scanning Electron Microscopes (SEM) • Use a beam of electron INSTEAD of light to produce a magnified image. • The resolution of SEM is MUCH BETTER than that of a light microscope • Can magnify a specimen up to 150,000 times its size.