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Transcript
Cell Structure and Function Chapter 7 Robert Hooke Anton van Leeuwenhoek "I have depicted the leaves at such a magnitude that you can see the globules ("tiny spots of different size") that lay within them. Actually, there are much more of these spots than I could depict in the drawing ; they are much smaller and not given in the right proportion. After cutting the leaf, those thin globules showed the very beautiful lightgreen color my eyes have ever seen. Some of them were darkgreen and their color were the black color of wax alike. Fig. BE is the part of the stem and the radix within which only very few green globules could be observed". --AvL http://www.euronet.nl/users/warnar/leeu wenhoek.html "That what I am observing is just what nature, not by sinfully defiling myself, but as a natural consequence of conjugal coitus..." Birth of Cell Theory 1855- German physician Rudolf Virchow concluded that new cells could be produced only from the division of existing cells 1883- German botanist Matthias Schleiden concluded that all plants were made of cells 1884- German biologist Theodor Schwann stated that all animals were made of cells Cell Theory All living things are composed of cells. Cells are the basic units of structure and function in living things. New cells are produced from existing cells. Prokaryotes Pro- before Karyon- “kernel” meaning the nucleus Cells that do not contain a nucleus lacking a distinct nucleus, such as bacteria, (pseudomonas sp) Pseudomonas sp Eukaryotes Eu- true or good Karyon- “kernel” meaning nucleus Cells that contain a true nucleus HSV 2 HSV 1 Cell Membrane Nucleus Contains nearly all the cell’s DNA and with it, the coded instructions for making proteins and other important molecules Controls the cell the way an office controls a factory Ribosomes Small particles of RNA and protein whose job it is to assemble proteins for the cell. “Factory machine” that follows instructions from the “boss” (nucleus) to produce proteins Endoplasmic Reticulum Site of assembly for lipid parts of the cell membrane as well as proteins and other materials for export from the cell Rough ER Rough ER is studded with ribosomes and works mainly on proteins Smooth ER Smooth ER performs specialized functions with lipids and detoxification of toxins and drugs Both types of Endoplasmic Reticulum function as factory machines producing materials at the instruction of the head office or boss in the nucleus Golgi Apparatus Modify, sort, and package proteins for storage, shipment, or export from the cell. Functions as a customization shop as well as packaging and shipping center for the factory. Lysosomes Used for multiple clean-up functions Filled with enzymes for breakdown of lipids, carbohydrates and proteins into small usable molecules for the cell Breakdown “junk” produced in the cell including old broken organelles Prions-When Lysosomes Fail The rogue proteins associated with Mad Cow Disease are resistant to degradation by lysosomal enzymes and so accumulate in the cell and cause disease. Vacuoles Saclike structure that stores materials such as water, salts, proteins, and carbohydrates Plants In many plant cells there is a single vacuole filled with liquid. The pressure of the vacuole in the cell helps support heavy structures such as leaves. Cell Walls Provide support and protection for the cell Cellulose is the main component of cell walls Vacuole Holding space inside a cell May hold food or water Helps maintain “turgor” in plants May help regulate water or provide movement in animal cells POWER!!! Mitochondria and Clhoroplasts Mitochondira are organelles that convert the chemical energy in food into the compounds the cell uses for energy Chloroplasts are organelles that capture energy from sunlight and convert it into chemical energy through photosynthesis Mitochondrion “powerhouse of the cell” Contains own DNA Chloroplast Plants often have both chloroplasts and mitochondria Both have their own DNA Endosymbiotic Theory Mitochondria and Chloroplasts each contain their own DNA separate from the nucleus of the cell Some scientists hypothesize that these organelles were originally prokaryotes that evolved a symbiotic relationship with other cells and eventually evolved into organelles. Endosymbiotic Theory Cytoskeleton • A network of protein filaments that helps the cell to maintain its shape and provide assistance for movement • Supporting structure and transportation system for the cell-factory • Made up of microfilaments and microtubules Cell Membrane Regulates what enters and leaves the cell and provides protection and support Double Often layered lipid bilayer contains embedded protein molecules as well as attached carbohydrates Concentration Solution is two substances, one dissolved in the other Concentration of a solution is the mass of solute in a volume of solution (mass/volume) 12 grams sugar in 3 L water (12g/3L) is 4g/L 12 grams sugar in 6 L water (12g/6L) is 2g/L The first solution is twice as concentrated as the second. Diffusion Particles move constantly. They tend to move from where they are more concentrated to where they are less concentrated. High concentration Low concentration Facilitated Diffusion Particles diffuse across the cell membrane through protein channels. Particles are too large to pass through the membrane itself. Moves down concentration gradient Costs no energy. Active Transport Actively pumps particles from one side of the cell membrane to the other Requires action and therefore costs the cell energy. Moves AGAINST the concentration gradient