Long Exam 1 Study Guide

Long Exam 1 Study Guide - Principles of Biochemistry Study...

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Principles of Biochemistry Study Guide – Chapters 11-16 (AKA: Dr. Long Exam 1) Chapter 11 Diffusion —transport of a solute through the membrane with no energy expenditure; occurs down the solute’s concentration gradient toward equilibrium Phospholipids —molecules with a polar head and nonpolar fatty acyl tails (one of which is unsaturated, kinked) that make up membrane bilayers with the nonpolar/hydrophobic tails toward the core and the polar/hydrophilic heads toward the intracellular and extracellular faces Hydropathy Index —test run on the primary structure of a protein in order to determine its membrane-spanning potential; hydrophobic residues are in peaks above the midline and hydrophilic below the midline Osmosis —spontaneous flow of water through a semipermeable membrane Liposome —vesicle formed by a phospholipid bilayer being suspended in aqueous solution, decreases edge instability; the beginnings of a cell Ionophore —molecule that binds to an ion to mask its charge and diffuse it through the membrane; can be very toxic because they can collapse ion gradients Active transport —movement of a solute across a membrane requiring energy; occurs up the solute’s concentration gradient and must be coupled to an exergonic reaction (like the dephosphorylation of ATP); loss of hydration sphere Micelle —formed by a single leaflet folding in on itself to create a ball—hydrophilic heads face outward and hydrophobic tail (only one—cone shaped) face toward the middle of the “ball” - Fluid mosaic model of biological membranes The phospholipid bilayer is the key element of the “fluid” part of the mosaic model, allowing the membrane to be flexible. The “mosaic” part of the model is thanks to the peripheral and integral proteins scattered throughout the membrane, held in place by non-covalent interactions. - Membrane architecture The bilayer is formed by two leaflets of phospholipids whose hydrophobic tails interact at the core. The hydrophobic tails consist of the fatty acid parts of the phospholipid. The two leaflets, in order to further stabilize themselves, form a sealed compartment (vesicle or liposome) that eventually becomes the cell. The hydrophilic heads of the phospholipids face outward and come into contact with the aqueous extracellular matrix and cytosol. Integral and peripheral proteins are scattered throughout the membrane with functional asymmetry—some face inward, some face outward, but all with a specific purpose. - Role of cholesterol in biological membranes The structure of the phospholipid has one “straight” saturated part of the tail and one “kinked” unsaturated part of the tail. This creates space between the phospholipids when they are lined up next to each other. Cholesterol fills these spaces to maintain the fluidity of the membrane and to keep it from leaking. Cholesterol is an animal product only and is an amphoteric molecule. -
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This note was uploaded on 12/10/2011 for the course BCH 5045 taught by Professor Guy during the Fall '08 term at University of Florida.

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Long Exam 1 Study Guide - Principles of Biochemistry Study...

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