TEST - BCMB 3100 Lecture 9 Horton Chapter 5 Review of...

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Unformatted text preview: BCMB 3100 Lecture 9 Horton Chapter 5 Review of Lectures 1-8 Test Monday Feb. 7 Bring at least two sharpened #2 pencils Lecture 10 Enzyme Properties Monday Feb 7 C127 at 5:00 pm Current biochemical generalization regarding living things 1. Life requires life 2. Biochemical reactions require catalysts 3. The information of life is transmitted in the genome 4. The Central Dogma of life information flow DNA RNA Protein Types of Cells Prokaryotic cells Bacteria contain no nucleus or intracellular membranes Eukaryotic cells Animals Contain a nucleus and intracellular membranes Eukaryotic cells Plants Contain a nucleus, chloroplasts and intracellular membranes. They also have a hard cell wall 1- Ion Pair (Salt-Bridge) Formal Charges 2- Hydrogen Bond (H-bond) Dipole-Dipole ( + , - ) 3- van der Waals (VDW) Induced Dipole 4- Hydrophobic Interaction Increase Water Entropy Reference C-C covalent bond Electrostatic Interactions Decreasing Strength 0.4 to 4 2 to 20 Energy (kJ mol-1 ) 20 to 40 3 to 10? variable 340 to 450 Summary of Non-covalent interactions Know this + - + - 0.28 nm ~ 40 to 200 kJ mol-1 Cl-1 Na +1 Formal Charges Non-Directional Charge is delocalized until salt bridge (or ion pair) is formed. Also called salt bridge or ion-pair interactions Charge-charge interactions Due to an asymmetric distribution of atoms with different electronegativities (H < C < N < O) . sp 3 Tetrahedron (slightly distorted) water = 1.8 Debye peptide = 3.5 Debye Molecular Diploes Strong Weak Weak 0.28 nm H-bond strength depends on: Distance D-H ---- A angle - - + - + - - + + Hydrogen Bonds sp 2 (planar) sp 3 Acceptor Donor (Salt Bridge) Donor + sp 3 (tetrahedral) ~ 2 to 20 kJ mol-1 As atoms approach each other they can induce weak dipoles called van der Waals induced dipoles as electrons move away from the approaching atom. + - + - + - + - ~0.36 to 0.44 nm E = ~0.4 to 4 kJ mol-1 van der Waals interactions G ice H-bonds ~23 kJ mol-1 In liquid water each water participates in ~2.4 H-bonds (simulations) Ice G = H - T S H-Bonding in Water and Ice G water H-bonds ~20 kJ mol-1 In ice each water participates in 4 H-bonds (hexagonal lattice) Water is polar and can form H-bonds *Some non-polar interactions are essential for life. Biological systems have water free microenvironments where non-polar interactions have maximal strength: e.g. lipid membranes *Molecules that are nonpolar (e.g. hydrocarbons) do not dissolved in water. They are called hydrophobic . *Nonpolar molecules or groups tend to cluster together in water = hydrophobic attractions; hydrophobic effect C 6 H 14 C 6 H 14 water hexane C 6 H 14 C 6 H 14 Two clustered hexane molecules Hydrophobic Interactions Molecules that are both hydrophilic and hydrophobic (e.g. lipids and detergents) A synthetic detergent A 12-carbon tail Polar sulfate group Sodium dodecyl sulfate (SDS) Amphipathic molecules...
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TEST - BCMB 3100 Lecture 9 Horton Chapter 5 Review of...

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