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Cell Boundaries. Pages 184-189. Cell Membrane. Function—regulates what enters and leaves the cell Core of cell membrane is a lipid bilayer. In addition to lipids, most cell membranes contain proteins that run through the lipid bilayer. Cell Wall.
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Cell Boundaries Pages 184-189
Cell Membrane • Function—regulates what enters and leaves the cell • Core of cell membrane is a lipid bilayer. • In addition to lipids, most cell membranes contain proteins that run through the lipid bilayer.
Cell Wall • Main function is to provide support and protection for the cell • Present in many organisms, including plants, algae, fungi, and many prokaryotes • Porous enough to allow water, oxygen, carbon dioxide through easily.
Diffusion • Diffusion—causes many substances to move across a cell membrane but does not require the cell to use energy. • Substances move with the concentration gradient. From an area of high concentration to an area of low concentration.
Osmosis • Osmosis is the diffusion of water through a selectively permeable membrane. • Selectively permeable—some substances can pass across while others cannot. • Water will move across the membrane until equilibrium is reached.
Osmotic pressure • Hypotonic solution—concentration of the substance is greater inside the cell. • Hypertonic solution—concentration of the substances is greater outside the cell. • Isotonic solution—concentration is equal inside and outside of the cell.
Facilitated Diffusion • Some molecules are too large to diffuse directly through the cell membrane. • Facilitated diffusion is the movement of specific molecules across cell membranes through protein channels. • Moves with concentration gradient • Proteins are specific to what they allow to cross. • Streaming video
Active Transport • Movement of particles from an area of low concentration to an area of high concentration. • Requires proteins in cell membrane • Requires use of energy
Movement of large amounts • Endocytosis—process of taking material into the cell by means of infoldings or pockets of the cell membrane • Phagocytosis—extensions of cytoplasm surround and engulf large particles. • Exocytosis—removal of large amounts of material from a cell.
Picture Credits • http://library.thinkquest.org/C004535/media/cell_membrane.gif • http://www.okc.cc.ok.us/biologylabs/Images/Cells_Membranes/diffusion.gif • http://www.himalayancrystalsalt.com/wellness/osmosis.gif • http://www.biologycorner.com/resources/hypotonic.gif • http://www.biologycorner.com/resources/hypertonic.gif • http://www.biologycorner.com/resources/isotonic.gif • http://faculty.abe.ufl.edu/~chyn/age2062/lect/lect_06/4_20A.GIF • http://fig.cox.miami.edu/~cmallery/150/memb/c8x16types-transport.jpg • http://fajerpc.magnet.fsu.edu/Education/2010/Lectures/12_Membrane_Transport_files/image032.jpg • http://sps.k12.ar.us/massengale/images/endocytosissmall.jpg • http://content.answers.com/main/content/wp/en/thumb/b/bc/400px-Phagocytosis.png • http://www.octc.kctcs.edu/gcaplan/anat/images/Image152.gif