02ab - CHAPTER 2 Living Cells Biochemistry: The Molecular...

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Biochemistry: The Molecular Basis of Life, 4/e McKee/McKee Copyright © 2009 by Oxford University Press, Inc. C H A P T E R 2 Living Cells
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FIGURE 2.1 Hydrophobic Interactions Between Water and a Nonpolar Substance 2.1 Basic concepts Cell – unit of life; complex biochemical factory that transforms matter and energy, respond to environ. stimuli and can reproduce itself. Membrane as a barrier and medium for interactions with environment and other cells. All cells: DNA as genetic information. Prokaryotic and eukaryotic (nuclear membrane) cells. Key concepts of cell structure and function : 1. Water 2. Biological membranes 3. Self-assembly 4. Molecular machines 5. Macromolecular crowding 6. Signal transduction 1. Water Polar structure, high concentration – necessity of life. Hydrophilic & hydrophobic molecules (exclusion): role in protein folding; spontaneous formation of phospholipid bilayers.
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FIGURE 2.2 Membrane Structure 2. Biological membranes thin, flexible, stable sheetlike structures that enclose cells and intracellular organelles. Functions: physico-chemical barrier; transport; information processing; energy generation Membrane structure: phospholipid bi layer containing embedded proteins. hydrophilic hydrophobic heads (fatty acid) tails Membrane proteins: - integral (embedded; hydrophobic aa): transporters, receptors - peripheral (loosely attached, or attached via a lipid linker) 3. Self-assembly - ability of components of large supramolecular machines to assemble spontaneously (eg ribosomes; chromosomes) due to complementary shapes and multiple weak interactions. FIGURE 2.3 Self-Assembly
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FIGURE 2.4 Biological Machines 4. Molecular machines Many macromolecular complexes have moving parts that perform work. Energy – due to hydrolysis of ATP (or GTP). 5. Macromolecular crowding Not a soup but a densely packed gel of macromolecules (protein concentration ~0.2-0.4 g/ml). Limited volume (excluded volume) occupied by macromolecules but available for small molecules. FIGURE 2.5 Volume Exclusion 6. Signal transduction process of receiving and interpreting information. Signals: physical (light, heat) and chemical. Three components of signal transduction:
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This note was uploaded on 10/14/2010 for the course MOLB 3610 taught by Professor Gomelsky during the Fall '10 term at Wyoming.

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02ab - CHAPTER 2 Living Cells Biochemistry: The Molecular...

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