Chapter 3.doc - BIO 111 Chapter 3 The Chemical Building Blocks of Life I MOLECULES ARE THE BUILDING BLOCKS OF LIFE Carbon is the framework of biological

Chapter 3.doc - BIO 111 Chapter 3 The Chemical Building...

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BIO 111 Chapter 3 The Chemical Building Blocks of Life I. MOLECULES ARE THE BUILDING BLOCKS OF LIFE : - Carbon : is the framework of biological molecules. It possesses 4 valence electrons. Organic compounds are based on Carbon’s need for 4 bonds to be stable . (and its tetrahedral structure) As a general rule, Carbon likes to have 4 bonds, Nitrogen likes 3, Oxygen likes 2, and Hydrogen likes 1. (96% of biological molecules are made of these 4 elements) - Biological Molecules consist predominantly of carbon atoms joined with other carbon atoms or atoms of oxygen, nitrogen, sulfur, or hydrogen. - The 3D shape of molecules adds to the diversity of molecules. A. Variation in carbon skeletons and their functional groups adds to the diversity of Organic Molecules a. Carbon Skeletons can have the following structures: straight, branched, or closed rings i. Hydrocarbons (non-polar) – biological molecules consisting of only carbon and hydrogen. Most living organisms do not have hydrocarbons in them, but many biological molecules have hydrocarbon tails (fats have this). b. Functional Groups : specific groups of atoms attached to carbon skeletons (organic molecules) - Functional groups behave consistently from one organic molecule to another - Functional groups are often involved in the chemical properties of a molecule and often bonding. Name of Functional Group (FG) Name of organic molecule w/ FG i) Hydroxyl group Alcohols - makes molecules polar —OH 1
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- water is attracted to hydroxyls, which helps to dissolve compounds containing them. ii) Carbonyl group O a) Aldehydes - nonpolar, which helps (if on end of organic ― C ― compounds) to dissolve in nonpolar substances. b) Ketones (if in the middle of compounds) O // iii) Carboxyl group ― C Carboxylic acids - proton donors in solutions \ - makes solutions more acidic OH H iv) Amino group / Amines - proton acceptors in solutions ― N - makes solutions more basic \ H v) Sulfhydryl group Thiols - help stabilize protein structure ― S ―H O vi) Phosphate group ― O ― P― O | Organic - transfers energy between organic O phosphates molecules - When not attached to an organic molecule, 2
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the phosphate group is called Inorganic Phosphate (Pi) H vii) Methyl group | - acts similarly to carbonyls ― C ― H Methylated - can be used to form amino acids | compounds H II. MAKING AND BREAKING MACROMOLECULES - Isomers : are alternative forms of the same substance (different structure with same molecular formula) a. Structural isomer : Different carbon skeleton b. Stereoisomer : Same carbon skeleton but differ on the arrangement of groups attached - Macromolecules are large, complex assemblies of molecules consisting of long chains of similar subunits.
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