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Transcript
Cell Structure and Function I Cell Theory • 1. All living things are made of cells. • 2. New cells are produced from existing cells • 3. Cells are the basic unit of structure and function in living things. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Cell Exploration • Light Microscopes – Living organisms can be seen – Light limits the resolution so extremely small things like proteins and viruses cannot be observed Cell Exploration • High resolution video technology – Allows scientists to see time elapsed movies of cells as the grow, divide and develop. – http://www.cellsalive.com/mitosis. htm Cell Exploration • Transmission Electron Microscopes (TEMs) – Can see more detain and extremely small structures – Beams of electrons must pass through ultra-thin sliced samples therefore no living things can be seen Cell Exploration • Scanning Electron Microscope (SEMs) – Beams of electrons scanned over the surface of a specimen – Produces a 3D image – Samples must be chemically preserved and removed of all water so no living things can be seen. Prokaryotes vs. Eukaryotes • Prokaryotes (bacteria) have no nucleus and very few organelles. DNA is not contained • Eukaryotes (protists, fungi, plants and animals) larger,more complex,DNA is inside the nucleus Plant Cells Vs. Animal Cells • Both plant and animal cells contain a variety of organelles. Some structures are specific to either plant cells or animal cells only. – Only plant cells contain: • Cell wall • Chloroplasts • Large central vacuoles – Only animal cells contain: • Centrioles Smooth ER vs. Rough ER • Rough ER - ribosomes on the ER make proteins, the ER modifies the proteins • Smooth ER - makes lipids Mitochondria vs. Chloroplasts • Mitochondria make energy from chemicals (food molecules) • Chloroplasts make energy from light through photosynthesis Cytoskeleton • Network of protein filaments • Maintains shape • Involved in cell movement Prokaryotes DNA is free floating Cell membrane Contain DNA Eukaryotes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell Structure and Function II Cell Wall • Provides support and protection for plant cell walls • Made of porous cellulose so it does not regulate what enters and leaves Cell Membrane • Regulates what enters and leaves the cell and provides support and protection • Structure – lipid bilayer with embedded proteins Diffusion through Cell Boundaries • Particles move from an area of high concentration to an area of lower concentration • No energy is required Osmosis • Diffusion of water through a selectively permeable membrane Is this really Osmosis??? Isotonic "ISO" means the same • Concentration of solutes (salts) is the same inside and outside of cell. • Water flows in and out in equal amounts • No effect on cell Hypertonic “Hyper” means more • Concentration of solutes is more outside the cell than inside • Water flows out of cell • The cell shrivels and may die. • This is why it is dangerous to drink sea water • This is also why "salting fields" was a common tactic during war, it would kill the crops in the field, thus causing food shortages. Hypotonic "HYPO" means less • Concentration of solutes is less outside the cell than in. • Water flows in • The cell swell with water and becomes “turgid” Active Transport • Carried our by protein pumps found in the membrane • Energy is required Facilitated Diffusion • Molecules move through protein channels. • No energy required Endocytosis • Cell takes material into cell by infolding of the cell membrane • Phagocytosis – eating – cell engulfs large particles • Pinocytosis – drinking – cell takes in liquid • www.endocyte.com/ animation/animation.htm Exocytosis • Cell releases large amounts of material Cell Specialization • The cells in multicellular organisms can develop in different ways to perform different tasks. Levels of Biological Organization • • • • • • • • Organism Organ system Organ Tissue Cell Organelle DNA Atoms