Zoology - N12507 - The Basic Unit of Life: The Cell Cell...

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The Basic Unit of Life: The Cell Cell Theory: 1. cells are the smallest living things; unicellular organisms 2. cells arise only by division of previously existing cells a. don’t just poof out of nowhere 3. all organisms are composed of one or more cells Cellular Basis of Life History: 1. Robert Hooke (1660’s) –observing cork tissue- coined term “cellulae” 2. Antonie van Leeuwenhoek (1670’s) used single lens microscope to observe  microorganisms found in the tartar scraped from his tooth—“animalcules” 3. Robert Brown (1830’s)—nucleus—largest unit in a cell 4. Mathias Shleiden (1839)—cells present in all plant tissues; nucleus somehow  important in reproduction 5. Theodor Schwann (1839) reported cells in animal tissue Shleiden and Schwann composed  the Cell Theory ; 1. all organisms are composed of one or more cells 2. the cell is the basic living unit of organization Virchow (1855) 3. all cells come from preexisting cells Cells must exhibit all the properties of life: Organization, metabolism, homeostasis, reproduction, growth, development,  irritability, and adaptabilty May stand alone or specialize(come together to become tissue) Size limited Two General Types; 1. Prokaryotes – lacks all membrane bound organelles, such as the  nucleus; do have DNA though 2. Eukaryotes – do have membrane bound organelles Three Domains; 1. bacteria 2. archaea 3. eukarya Six Kingdoms 1. bacteria
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2. archaea
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Zoology - N12507 - The Basic Unit of Life: The Cell Cell...

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