Cell Structure and Function Chapter 7
Ch 7.1-Life is Cellular
How Did We Discover Cells? Microscopes! Invented in the late 1500s Antoni van Leeuwenhoek (1600s) Created some of the best early lenses Submitted drawings of tiny living things he called “animalcules”
Who Called Them “Cells”? Robert Hooke (1600s) Observed cork Empty boxes looked like monastery cells to him Inspired the name for cells
The Cell Theory - Matthias Schleiden (1800s) - Theodor Schwann (1800s) Stated that all plants are made of cells - Theodor Schwann (1800s) Stated that all animals are made of cells - Rudolf Virchow (1800s) Cells can only be produced by existing cells
The Cell Theory 1) All living things are made up of cells 2) Cells are the basic units of structure and function in living things 3) New cells are produced from existing cells
Light Microscopes Allow light to pass through a specimen Use lenses to magnify a specimen Ocular lens is the lens you look through Objective lens is the lens above the specimen Compound Microscope Dissecting Microscope
Cell Stains Most living cells are transparent Staining cells can make them visible Some stains work on entire cells, and some only on parts of a cell - Some stains are fluorescent
Electron Microscopes Use electrons instead of light Can show much greater detail than light microscopes - Images are in black and white Computers are used to add “false color”
Transmission Electron Microscopes Pass electrons through a really thin specimen Specimens are cut into ultra-thin flat slices
Scanning Electron Microscopes Bounce electrons off the surface of a specimen - Show the 3-D outline of a specimen
Types of Cells Prokaryotes Eukaryotes - Do not enclose DNA in a nucleus - Always unicellular - Smaller, simpler cells - Enclose DNA in a nucleus - Can be unicellular or multicellular - Larger, more complex cells