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Plant and Animal Cells SNC2D The Cell – The Unit of Life • The cell is the basic structural and functional unit of all known living organisms. • Organisms can be classified as unicellular (consisting of a single cell; including most bacteria) or multicellular (including plants and animals). • Humans contain about 10 trillion cells. • Most plant and animal cells are between 1 and 100 µm and therefore are visible only under the microscope. The Cell Theory The cell was discovered by Robert Hooke in 1665. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that: 1.All living organisms are composed of one or more cells. 2.Cells are the basic units of structure and function in all organisms. 3.All cells come from previously existing cells. Prokaryote or Eukaryote? • Prokaryote A cell that does not contain a nucleus or other membrane bound organelles o E.g. Bacteria o • Eukaryote A cell that contains a nucleus and other organelles, each surrounded by a membrane o E.g. Animal or plant cell o Bacteria (Prokaryote) Plant Cell (Eukaryote) Animal Cell (Eukaryote) Structure & Function • The function of the organelles is very closely related to its structure. o For example, the golgi bodies look like a stack of flattened pancakes (this is their structure). This is because they are hollow sacs, where proteins can be placed. • Activity: Pairs o Select 3 organelles from your table and answer the question: How does its structure allow it to carry out its function? • The relationship between structure and function is an important one in this unit. Be sure to consider both when responding to a question. Thinking Questions • How can our understanding of cells and organelles help us fight health conditions and develop strategies to lead healthier lifestyles? • Can you think of any medical advances that would require enhanced knowledge of cells and their organelles? Credits • • • • • • http://commons.wikimedia.org/wiki/File:SEM_blood_cells.jpg http://commons.wikimedia.org/wiki/File:Lactose_non_lactose_fermenters_on_CLED_agar.jpg http://commons.wikimedia.org/wiki/File:Normal_Epidermis_and_Dermis_with_Intradermal_Ne vus_10x-cropped.JPG http://commons.wikimedia.org/wiki/File:Average_prokaryote_cell-_en.svg http://commons.wikimedia.org/wiki/File:Plant_cell_structure_svg.svg http://commons.wikimedia.org/wiki/File:Animal_cell_structure_en.svg