Cell Biology, Week 4
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This 6 page Class Notes was uploaded by Pratiti Ghosh-Dastidar on Sunday September 25, 2016. The Class Notes belongs to BIO203 at Miami University taught by Dr. James in Fall 2016. Since its upload, it has received 6 views. For similar materials see Cell Biology in Biology at Miami University.
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Date Created: 09/25/16
Pg – 34 Strength of interaction: Lot of binding molecules is based on # of the weak interactions and shape of binding site Determine binding affinity Strength of interaction determines the relative time in complex. Quantifying strength of interaction ~ based on equilibrium Constant ~ rate of association over rate of disassociation Chapter 11: Membrane Structure Prokaryotes only have 1 membrane that regulate and comp of cell interior Eukaryotes have internal membranes that regulate not only comp of cell interior but also regulate what’s in the organelles thus compartmentalizing cell more efficient. Plasma membrane function almost are same for internal membrane o Structure of phospholipid bilayer embedded proteins give specific function. Receptor protein respond or bond to stimuli from outside cell can transmit into the cell. V. important for movement or things in and out of cell efficent barrier Pg -35 Ex) waste products (usually H2) soluble) transport out nutrients for cell (also H2O Soluable) transport in. Can change shape allowing for expansion, or if it can spontaneously seal itself maintain barrier function. o Can deform w/ help of cytoskeletal elements aids motility of cell. Proteins membrane: o Selective barrier choses specific molecules/ions to get in semi permissible membrane. Fluid Mosaic Model: “Proteins floating in sea of lipids” Major Components: Phospholipids Its amphipathicity also for its unique functions. Other membrane lipids o Sterols (in animals), glycolipids (spingolipids) Pg – 36 Plasmogen Phosogycerides o 1 fatty alcohol (C 1 A lot have double bond b/w 1 bond. Believed to prevent oxidation. Sphingolipids o Derived from sphingosine Amino alcohol o Sphingosine + fatty acid = ceramide o Then attach phosphocoline Ex) shpingomyelin Most abundant sphingolipid Phosphocholine group attached to hydroxyl group of sphingosine Is a phospholipid Similar structure to PC Pg- 37 In H2O phos. Lipids spontaneous rearrange to form sealed structure so part maximizes interaction w/H2O and part minimize interaction w/ H2O o Key Property: o Folds onto itself to form a sphere called liposome o cant do this b/c its NOTE is only single layered Types of movement Lateral diffusion Stays on same face of membrane Flexion Movement tail Rotation Flip-flop rarely occurs b/c of properties. More stable to stay same face. No real attractive force to move it across membrane Membrane Fluidity o Phospholipids proteins can have go where its needed, proteins evolved to function based on fluidity o Viscosity thickness stickiness of (resistence of fluidity) o Transition temperature: Temp @ which subs gains or loses fluidity Freezing point: liquid solid Melting point solid liquid Referred as . o Depends on Lipid composition and amount of cholesterol Pg - 38 Sterols (Cholesterols) Fills in spaces where theirs kinks in fatty acids Serves as buffer causing rigidity Temp = prevents too fluidity Temp = don’t exactly fit = keeps from packing as much as possible – prevents becoming too gel-like.