ELEMENTS OF BIOL CHEM
ELEMENTS OF BIOL CHEM BICH 303
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This 14 page Class Notes was uploaded by Ceasar Fritsch on Wednesday October 21, 2015. The Class Notes belongs to BICH 303 at Texas A&M University taught by Timothy Devarenne in Fall. Since its upload, it has received 27 views. For similar materials see /class/225849/bich-303-texas-a-m-university in Biochemistry at Texas A&M University.
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Date Created: 10/21/15
The Hydrogen Bond Covalent bond a chemical bond characterized by the sharing of electron pairs between atoms exampleC H O H Hydrogen bond a noncovalent interaction characterized by electrostatic attraction between a H atom and the unshared electrons of an electronegative atom such as O or N HO hydrogenboud donor H Linear 1 Nonlinear hydrogen bond acceptor aaaaaaaaaaaaaaaaaaaa m Hbond donor the H covalently bound to a electronegative atom Hbond acceptor the electronegative atom that contributes the unshared electron pair The Hydrogen Bond When H is covalently bound to electronegative atom such as O or N it gives the H a partial charge such with in H20 This partial of H can then interact with the unpaired electrons of electronegative atoms acceptors I I I I F acceptors Consider HF H20 and NH3 donors H IliquotH 3vH EH 3 HF H one donor F three acceptor sites H45 H5 H20 H two donors 139 139 l1 139 0 two acceptor sites acceptor NH3 H three donors if if N once acceptor H N Hquotquot N Hquotquot N Hquot NH l H H H H donors aaaaaaaaaaaaaaaaa mm The Hydrogen Bond Strength of Hbond Energyquot Type of Bond kJ molquot kcal molquot Covalent Bonds Strong O H 460 110 H H 416 100 C H 413 105 Nonovalcnt Bonds Weaker Hydrogen bond 20 5 Ion dipole interaction 20 5 Hydrophobic inLerac Lion 4 1 2 1 Van der Waals interactions 4 1 muss EwanCare rThwmssm The Hydrogen Bond Hbonding in H20 Each H20 molecule is Hbonded to 4 other H20 molecules two as acceptor O and two as donor H mmmmmmmmmmmmm Thmwswn The Hydrogen Bond Hbonding in H20 acceptors H EhnH EhquotH F acceptors donors H HII5H H395 E1 H 14 H Ha3 HquotHg5Hgl5 H H H H acceptor i i i H flx39i H IT H I H T H H H H H donors LL Substance Unique Hbonding in H20 accounts for its high melting and boiling points Molecular Weight Melting Point C Boiling Point C Water H10 802 00 1000 Ammunia NHJ 1703 777 33L Methane 3H H304 71325 71615 The Hydrogen Bond The importance H20 ofto life Due to the polar nature ofwater polar solutes can dissolve in H20 by Hbonding with H20 Between a hydruvyl group Benveeu a arbnnyl grole Between an amino group of an alcohol and H20 ofa kemne and H20 c an amine and H20 1K0 RcR39 RNH l hydmgen hmld donnrl ll lbwlrngw huml adaptor l hydrogen bond dnunrl H 0 H hydro en band acne mr 3 c hylxngeu band ccepmr H KH g P Iquot hydrogen buml donor H H H 2905 raakleule rl39v mmsun The Hydrogen Bond The importance H20 of to life Helps to stabilize the 3D structure of molecules Proteins DNA Hbonding between amino acid side chains Hbonding between nucleotide within a protein and between proteins bases of DNA strands Types of hydrogen bonding in proteins Hydrogen bonds between the strands of a DNA double helix Interstrand Intrastranzl Interstrand re an Rmnkxlf nlmrnmmmn Thermodynamics in Relation to Biochemistry Thermodynamics is a branch of physics which deals with the energy and work of a system Within a system biological processes that release energy are favored Processes that require energy are not favored Spontaneous process reaction which occurs without input of energy energy released does not mean instantaneous Nonspontaneous requires input of energy for process reaction to occur energy required Thermodynamics in Relation to Biochemistry 1ST law of thermodynamics matter energy can be neither created or destroyed Can only be transferred law of conservation of energy Process that releases energy spontaneous hydrolysrs of ATP v 7 Start 2 HzO ll 1 ATP N V x N 3 60 0 r N 0 r N ll ll ll ll l OiPiOi O P O CII2 0I OP07IUZ l l 7 7 V 0 L 4 H ll 0 i Hi H l 0 ATP ADP Ll nusinvu39iphusphmu Phosplmlc ludenosiuelipllusplmm P ADI l husplmlcinu E70058 mum iiiiiiiiiiiiiii m 80 energy released from ATP hydrolysis is used to drive less energy favorable nonspontaneous reactions Thermodynamics in Relation to Biochemistry Free energy of a system A measurement of amount of work energy within a system A way to measure the spontaneity of a process or reaction Gibbs free energy AG the work exchanged by the system with its surroundings J VWliam Gibbs 1839 1903 Yale University Laid foundation of chemical thermodynamics and physical chemistry Thermodynamics in Relation to Biochemistry Values of AG in relation to spontaneity AG lt 0 process reaction is spontaneous exergonic releases energy free energy of the process decreases AG O equilibrium AG gt 0 process reaction is nonspontaneous endergonic energy required free energy of the process increases Spontaneous process metabolism of glucose glucose 6 02 gt6 002 6 H20 AG lt 0 releases energy Nonspontaneous process formation of ATP ADP HPO4 H gt ATP H20 AG gt 0 requires energy Thermodynamics in Relation to Biochemistry OrderDisorder Entropy AS 2nd law of thermodynamics a measure of disorder in the universe a direct measure of the randomness of a system the higher the entropy the greater the disorder systems tend toward disorder organisms are constantly trying to increase order fight entropy 2nd law of thermodynamics spontaneous processes occur in directions that increase the overall disorder of the system A ordered I A disordered V V spontaneous NH Hp Mtg hydrolysis of ATP VIN N l lt I J N N 0 0 N i il i l i 1 7 1 foi ioiui 1 Y 0 0 If Y O lt o gt11 01 70711707 t H on on ADP indemniin lliplluspllaml Thermodynamics in Relation to Biochemistry OrderDisorder Consider Glass of ice water Ice is very ordered low entropy Will tend to become less ordered by ice melting increasing entropy until equilibrium is met Thermodynamics in Relation to Biochemistry Protein Folding Force driving protein folding is Entropy Protein folding a spontaneous process AG lt 0 tends to increase the entropy of surrounding solution creates a favorable situation thermodynamically Order within the protein is traded for disorder outside of the protein We will deal with this more at a later date