1 Biochemistry 3010 Lecture 1 Lecture Overview (1) Elements Involved in Biological Systems (2) Cellular Components and Organization (3) Non-Covalent Interactions (4) H20 Biochemistry multidisciplinary study investigating structure, function and organization of molecules that compose living systems 3 Main Areas of Investigation (overlap) (i) Structural Chemistry (ii) Metabolism (iii) Chemical Processes Related to Storage and Transmission of Biological Information 2 (1) In Biochemistry need to know: - Chemical Structures - Stoichiometry and Mechanism - Thermodynamics - Kinetics Elements in Our World Earth's Crust Human Body O 47% H 63.0% Si 28 O 25.5 Al 7.9 C 9.5 Fe 4.5 N 1.4 Ca 3.5 Ca 0.31 Na 2.5 P 0.22 K 2.5 Cl 0.09 Mg 2.2 K 0.09 Ti 0.46 S 0.09 H 0.22 Na 0.09 C 0.19 Mg 0.09 H, O, C and N lightest elements capable of forming 1, 2, 3 and 4 bonds some of the strongest bonds are made by the lightest elements 3 (2) Cellular Components and Organization (i) The most important inorganic molecule H20 (ii) Organic Biomolecules (a) Proteins (Structure, Function) (b) Nucleic Acids (DNA, RNA) (c) Carbohydrates (cellulose, starch, glucose) (d) Lipids (Fat, Membrane components) (iii) Minerals (Ca2+, Fe2+, Mg2+, K+) (a) Proteins - found throughout all cells - greatest variety in cells - ~50% of solid material in cell - 2-3 million molecules/cell - 2000-3000 different proteins ( ) - composed of a combination of 20 different amino acids - 4 (b) Nucleic Acids (DNA, RNA) - largest biomolecule in cell - ~ 1% of a cell's weight (~3% of dry weight) - fundamental information storage molecules DNA Transcription RNA polypeptide Translation (3) Non-Covalent Interactions Covalent bonds hold molecules together H2O Weak forces (4-30 kJ/mol) cannot form inter-atom bonds, but the cumulative interactions create greater stability Constantly forming, disintegrating and reforming in biological systems 5 (i) van der Waals non-specific attractive force when two atoms (or groups of atoms) are 3-4 apart - the distribution of electronic charge around an atom (or group of atoms) changes with time (ii) Hydrogen Bonding - form between an H atom covalently attached to an electronegative atom (O or N) and a second electronegative atom that serves as H bond acceptor (O or N lone pair electrons). =C=O HN= 2.7 (one H acceptor and one donor) - Range from 12 to 30 kJ/mol (3-7 kcal/mol) (Stronger than van der Waals) - Directional properties (-helix stability) 6 7 H bonds are highly directional O-H ------O A Strong H Bond because the donor and acceptor are co-linear - Bonds that are at angles are weaker bonds e.g. H bonds are important in stabilizing the -helix of a protein -The hydrogen donor is more tightly associated with H In biological systems hydrogen is covalently linked to O or N -The hydrogen acceptor has a partial charge and can be either O or N (in biological systems) H bond range = 3 7 kcal/mol H bond length = 2.7-3.1 8 (iii) Ionic Interactions - forces between charged groups (+) (-) --+NH3 - O-CO- --+NH3 --+NH3 - may involve ions, permanent dipoles or induced dipoles (iv) <a href="/keyword/hydrophobic-interactions/" >hydrophobic interactions</a> -Nonpolar solutes do not H bond with water and thus are difficult to solubilize - Dissolving such cpds require reorganization of water molecules which surround them - Reorganization results in forming cage like structures or clathrates This hydration shell results in ordering of structure or negative entropy. - Hydrophobic interaction arise when 2 nonpolar molecules come in contact. 9 - It is energetically more favorable to have 2 hexane molecules in a single cavity (clathrate) because less H2O molecules have to be `ordered' in this situation ** The basis of a hydrophobic interaction is the enhanced freedom of released water molecules (that were previoulsy ordered)** Always remember The hydrophobic interaction is not really a bond 10 (4) Water and Biomolecular Interactions **water influences all molecular interactions i...