Cell Membrane Structure and Cell Transport HOW DO
Cell Membrane Structure and Cell Transport HOW DO MATERIALS GET ACROSS THE CELL MEMBRANE
Structure of the Cell Membrane Cell membrane is a fluid structure (not rigid) Selectively Only permeable lets certain substances in and out of the cell
Structure of the Cell Membrane
Structure of the Cell Membrane Remember lipids are nonpolar Cell membrane has a polar head (water loving) and a nonpolar tail (water fearing). PHOSPHOLIPID BILAYER – Allow lipids and other substances that dissolve in lipids to pass through, BUT water can also go through the cell membrane (even though it is polar)
Structure of the Cell Membrane Proteins embedded in the cell membrane. Remember: proteins are made of long chains of amino acids – some of those amino acids are polar and some are nonpolar Attraction between the polar amino acids and the polar heads and the nonpolar amino acids and the nonpolar tails keeps the proteins embedded
Structure of the Cell Membrane Transporter Proteins Receptor Proteins Two Receive types: Channel proteins and carrier proteins Let things that are large and polar into and out of the cell environmental signals (such as hormones) and bring them into the cell
Cell Transport Passive Transport No energy is required Two types: Diffusion Simple Facilitated Osmosis Active Transport Energy is required (ATP) Two types: Protein pumps – (specific type of transport protein) Bulk transport Endocytosis Exocytosis
Passive Transport – Simple Diffusion Substances move from an area of “high” concentration to an area of “low concentration” Move down the concentration gradient Diffusion occurs until equilibrium has been reached – equal concentration on both sides of a cell membrane
Passive Transport – Facilitated Diffusion Still passive transport Still moving from an area of high concentration to an area of low concentration until equilibrium is reached Difference – a transport protein is needed for the substance to get across the cell membrane
Passive Transport – Simple Diffusion vs. Facilitated Diffusion
Passive Transport – Osmosis (diffusion of water) Isotonic – balance of water (equal) Hypotonic – water moves in Hypertonic – water moves out
Osmosis (diffusion of water) - hyponatremia Jennifer Strange’s Stomach
Osmosis (diffusion of water) - hyponatremia Brittney Chambers of Colorado (2001), Leah Betts of Great Britain (1995), and Anna Wood of Australia (1995) died after reportedly taking Ecstasy and drinking large amounts of water. Fraternity hazing killed Matthew Carrington, a student at California State Chico February 2005. In Sacramento, Jennifer Strange died after a water-drinking contest "Hold your wee for a Wii” sponsored by a local radio station, January 2007. A 28 -year-old female Boston marathoner died in 2002. Artist Andy Warhol died after hospital staff accidentally administered excess water after gall bladder surgery (1987). Infants fed diluted formula for extended periods of time can suffer from hyponatremia.
Active Transport - ATP Energy unit Nucleic acid (macromolecule – DNA, RNA and ATP) Made of nucleotides Nitrogen base Sugar Phosphate group
Active Transport - ATP Energy When is stored in these bonds break, an enormous amount of energy is released
Active Transport – Using a protein pump Requires use of protein pump (transport protein) in cell membrane Substances moves from an area of low concentration to an area of high concentration Moves AGAINST the concentration gradient
Active Transport – Bulk Transport Movement of large macromolecules (proteins/complex carbs) across cell membrane Endocytosis Cell membrane engulfs a substance and pinches off to form a vesicle Brings substances INTO a cell Exocytosis Vesicle fuses with cell membrane Brings substances OUT (EXTERIOR) of a cell
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