Chapter 3 - Chapter Outline - The Chemistry of Life

Chapter 3 - Chapter Outline - The Chemistry of Life - Purav...


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Purav Patel Chapter 3 AP Biology The Chemistry of Life: Organic Compounds Introduction Organic Compounds - compounds in which covalently bonded carbon atoms form a backbone Organic Compounds can only be produced by living organisms; 5 million have been identified. This diversity is made possible by the varied 3-D shapes organic compounds can form and the ability of carbon atoms to bond with many kind elements. The additional chemical groups added to the organic molecule create the properties of organic molecules. Macromolecules - large organic molecules constructed by cells from simpler subunits Major Groups of Biologically Important Organic Compounds: 1. Carbohydrates 2. Nucleic Acids (DNA/RNA) 3. Lipids 4. Proteins Carbon Atoms and Molecules Carbon atoms use their four valence electrons to form four covalent bonds and fill their shells. Since carbon-carbon bonds are strong, the atom is suitable for being the backbone of molecules. Hydrocarbons - organic compounds made of carbon and hydrogen; can be rings or chains The shapes of molecules dictate biological properties and functions. There is a degree of flexibility between around carbon-carbon single bonds in organic molecules. This allows for a variety of shapes and molecules to form. Double and triple bonds hinder rotation, being inflexible. Isomers Have the Same Molecular Formula, But Different Structures Isomers - compounds with the same molecular formula but differently structured 1. Structural Isomer - compounds differing in covalent arrangements of atoms a. In C 2 H 6 O, ethanol or dimethyl ether may be formed. 2. Geometric Isomer - compounds differing in their spatial arrangement of atoms a. Examples include cis, trans- isomers; they feature double bonds. 3. Enantiomer - molecules that are mirror images of one another a. Mirror reflection of one molecule (methane). They’re nonsuperimposable. 1
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Purav Patel Chapter 3 AP Biology Functional Groups Change the Properties of Organic Molecules Hydrophobic - “water fearing”; insoluble in water Example: Hydrocarbons, being nonpolar, cluster together after being repelled by water. Functional groups - groups of atoms determining the types of chemical reactions and association in which a compound participates Hydrophilic - “water loving”; associating strongly with polar water molecules The properties of biologically important molecules are a result of the types of arrangement of functional groups they contain. The hydroxyl group is considered polar, because the strongly electronegative oxygen atom is present. Carbonyl Group - carbon atom with a double covalent bond to an oxygen atom Aldehyde - a carbonyl group is attached to a carbon chain ( R-CHO ) Ketone - a carbon chain with carbonyl group embedded inside (R -CO-R) Carboxyl Group - a double covalent bond links a carbon atom to an oxygen atom (weak acids) Amino Group ( R-NH 2 ) ; weak bases; they are components of amino acids and nucleic acids Phosphate Group - ( R-PO 4 H 2 ) ; weak acid; ½ hydrogen ions may be released; negatively charged
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