Biology Week 4 notes
Biology Week 4 notes BIOL 107-06
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This 2 page Class Notes was uploaded by emmy_rose4267 on Friday September 16, 2016. The Class Notes belongs to BIOL 107-06 at Truman State University taught by Daniela Ostrowski in Fall 2016. Since its upload, it has received 3 views. For similar materials see Introduction to Biology I in Biology at Truman State University.
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Date Created: 09/16/16
Intro to Biology 9/13 EXAM DAY 9/15 Cell Membrane Lipid bilayer: formed when 2 sheets of lipid molecules align Membrane permeability: how fast molecules can move from one side to the other Small, nonpolar and uncharged molecules can easily cross a lipid layer (diffuse) DNA does not go through a membrane Amino acids can go through but go slowly, rates vary on their side chain Lipid bilayers that are short and unsaturated have a high permeability while long and saturated have a lower because it creates a longer barrier Heat makes them move faster, making it not as tight so higher permeability Cholesterol decreases the permeability of membrane Crossing the Lipid Bilayer 1) Diffusion: movements of molecules and ions that result their kinetic energy Concentration gradient: difference in solute concentration Molecules get equally distributed across the membrane The higher temperature makes diffusion easier and go faster 2) Osmosis: movement of water and holds back solutes Water can cross the membrane quickly Hypotonic: less ions on the inside the cell, losing water from inside the cell making it shrink Hypertonic: has a lot of ions inside the cell, water flow inside cell making it burst Isotonic: Equal inside and outside solutions and concentration, water can flow in and out 3) Membrane proteins Proteins that are amphipathic can be inserted into lipid bilayers and form channels or pores across the lipid bilayer The ends of the polypeptide chains should be polar and middle should be nonpolar 1) Integral proteins: span the membrane A) Channels: ions can move through ion channels from regions of high concentration to lower Electrochemical gradient: concentration and electrical gradient They are selective and can be gated Passive transport powered by diffusion B) Carrier: undergo conformational change after substrate binding (bind on one side, protein changes, brings stuff into the cell) Crossing through membrane through diffusion C) Pump: used to transport molecules against the gradient (active transport) ATP provides energy for the process (hit your foot, it is what stops it from hurting forever) 2) Peripheral proteins: bound to the membrane without passing through it 3)
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