I. Cell History A. Anton Leewenhock (1600s) - first person to observe cells - in pond water, using a homemade microscope B. Robert Hooke (1665) - observed many kinds of animal tissue under a microscope - concludes that all animals are made up of cells C. Schwann (1868) - observed many kinds of animal tissue - concludes that all animals are made up of cells D. Schleiden (1869) - observed many kinds of plant tissue - concludes that all plants are made up of cells E. Cell Theory - came about from the work of Schleiden and Schwann Two major points: 1. All organisms are made up of one or more cells 2. Cells come from only pre-existing cells
**When it comes to studying life, all living things have something in common. Cells provide the basic for studying all life.
F. Cell Variation 1. Cells vary in size and shape 2. vary in shape G. Cell organization in organisms 1. Unicellular 2. Colonial Multicellular - live together but can be independent 3. other multicellular organisms have specialized cells organized as follows: Specialized Cells - cells that perform one or few functions very well. Examples: white blood cells, red blood cells, muscle cells, nerve cells. Tissue - Groups of specialized cells that work together Organ - groups of tissues that work together Organ System - groups of organs that work together
II. Parts of a cell : all cell parts have functions A. Parts found in all cells 1. Cell membrane - two layers of lipids with proteins embedded a. function : regulates what enters and leaves the cell b. selectively permeable - allows some molecules to pass through but not others c. Factory analogy = security 2. Cytoplasm - gelatin-like substance inside cells that hold all cell parts together - mostly water 3. Ribosomes - very small structures made of RNA and