Bio 1201 exam 2 Gregg latest update graded A+

Bio 1201 exam 2 Gregg latest update graded A+ transport proteins are responsible for controlling passage across the membrane fluid mosaic model The membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids fatty acid tails nonpolar, hydrophobic fatty acid heads hydrophilic, polar periphial proteins bound to the surface of the membrane integral proteins penetrate the hydrophobic core (ones that span the membrane are transmembrane protiens How do cells recognize each other? by binding to molecules, often containing carbohydrates, on the extracellular surface of the plasma membrane Glycolipids Membrane carbohydrates that are covalently bonded to lipids. Hypdrophobic molecules such as hydrocarbons that can dissolve in the lipid bilayer and pass through the membrane rapidly Hydrophilic molecules that don't cross the membrane easily (ions and polar molecules) transport proteins allow passage of hydrophilic substances across the membrane carrier proteins bind to molecules and change shape to shuttle them across the membrane passive transport the diffusion of a substance across a membrane with no energy investment Diffusuion Spreading out of particles away from each other, from an area of high concentration to an area of low concentration. (move to where space is available) concentation gradient substances diffuse from high concentration----> low concentration Osmosis Diffusion of water through a selectively permeable membrane Isotonic when the concentration of two solutions is the same (no net movement) Hypertonic cell losses water and shrivils hypertonic cell gains water and expands In a plant cell water moves in and out affecting the size of what? central vacuole facilitated diffusion the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins ion channels channel proteins that transport ions gated channels open or close in response to a stimulus