3ObjectivesSWBAT explain how microscopes came into use and the early observations that were made by scientists.SWBAT describe the three steps of the Cell Theory.SWBAT describe some modern microscope techniques used to look at cells and their parts.SWBAT explain how cells are classified.SWBAT describe the differences between prokaryotes and eukaryotes.
4Discovering the CellMid 1600’s: scientists began to use microscopes to observe living things.1665: Robert Hooke (England) compound scope1674: Anton van Leeuwenhoek (Holland) single lens scope.
5Cell Theory Cell Theory states… 1) All living things are composed of cells.2) Cells are the basic unit of structure and function in living things.3) New cells are produced from existing cells.
6Exploring the Cell Today Today’s researchers use microscopes and techniques that are much more powerful than those of early scientists.Examples: fluorescent labeling, light microscopes, 3-D imaging using electron microscopes
8Electron Microscopes SEM : Scanning Electron Microscope Scanning a pencil-like beam of electrons over the surface of an object. Produce a 3-d imageTEM : Transmission Electron MicroscopeThe transmission electron microscope (TEM) operates on the same basic principles as the light microscope but uses electrons instead of light.
9TEM resource SEM resources Pictures From The TEMSEM resourcesscharfphoto.com: David Scharf: HomePictures From The SEM
10Classifying Cells Variety of shapes and sizes. Typical cell 5- 50 µm. 2 common characteristics:Surrounded by barrier- cell membraneAt some point in the cell lifespan they contain the molecule that carries biological information- DNA.
11How small is a micrometer (um)? 1 micrometer (um) is one millionth of a meter 1/1,000,000 mor 1 x 10-6
13Classifying Cells cont’d 2 categories of cells- depend upon whether they contain a nucleus.Eukaryotes: contain nucleiProkaryotes: no nucleusNucleus: large membrane-enclosed structure that contains cell’s genetic material (nucleic acids) in the form of DNA.Controls many of the cell’s activities.
15Prokaryotes Smaller and simpler than eukaryotes. No nucleus. Some contain organelles.Carry out every activity associated with living things.Grow, reproduce, respond to environment, glide, and swimExample: Bacteria