Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
What is the chemical basis of life? • What are some of the ideas central to the chemistry of life? • (Key concepts of the chemical basis of life) How does water do all this? What allows water to facilitate life at the cellular and global level? Hydrogen Bonds • A weak force of attraction between the H on one molecule and a highly electronegative atom on another molecule Extraordinary Properties of Water • Versatile Solvent-------due to polarity • • • • Adhesion and Cohesion---due to H bonds High Specific Heat --------due to H bonds High Heat of Vap. ---------due to H bonds Expands when freezing ---due to H bonds Ideas central to the chem of life • • • • • • Based on covalent bonding Carbon is the “backbone” of biomolecules Simple building code Variation on common theme in extreme Only 4 fundamental types of biomolecules Enzymes make and break the covalent bonds in the chemical reactions in the cell • Isomers and polymers • Condensation and Hydrolysis Famous ions in Biology • • • • • Hydronium H3O+ and Hydroxide OHPotassium K+ ions Sodium Na+ ions Calcium Ca2+ ions Hydrogen H+ ions (protons) Elements Essential to Life • About 25 of the 92 natural occurring elements are essential to life • CHON = 96% liv mat • CHONPS = > 99% A continuum view of bonding • Atoms complete their valence shell in a continuum of: • Nonpolar covalent with equal sharing of e– Examples: H—H O=O • Polar covalent, unequal sharing of e– Examples: H2O NH3 • Ionic, with complete transfer of e– Examples: NaCl Al2O3 Weak Bonds are Bio’ly Important • H bonds, hydrophobic interactions, etc • Can form between different parts of a single large molecule or between molecules • Help stabilize 3D shape of proteins & Nas • Function in chemical signaling • Hold enzymes to substrates Biological Building Codes • Covalent Bond= shared pair of electrons between 2 nonmetals • H, 1 unpaired e• O, 2 unpaired e• N, 3 unpaired e• C, 4 unpaired e- Versatility of Carbon • 4 valence electrons • Compatibility with many different el’s • S, D, T bonds • Makes large, complex molecules possible – Strait chains – Branched chains – Rings • Polymer • (poly = many; mer = part) • Large molecules consisting of many similar subunits connected together • Monomer = subunit or building block of polymer Macromolecules are Polymers • • • • Carbohydrates = polymer of monosaccharides Lipids = polymer of fatty acids & glycerol Proteins = polymer of amino acids Nucleic Acids = polymer of nucleotides Polymers & Molecular Diversity • Unity in life: Only about 40 or 50 common monomers build macromolecules • Diversity in life: New properties emerge when these monomers are arranged in different ways Sucrose Synthesis Hydrolysis Making & Breaking Polymers animation • • • • • Dehydration synthesis Link monomers Via removal of H2O 1 water per link (out) One monomer lose OH, other loses H • Any assembling of molecules in cells • • • • • Hydrolysis Disassemble polymers Via addition of H2O 1 water per link (in) One monomer gains OH, other gains H • Any disassembly of molecules in cells