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The Structure and Function of Macromolecules II. Classes of Organic Molecules: • What are the four classes of organic molecules? I. Polymers • What is a polymer? • Poly = many; mer = part. A polymer is a large molecule consisting of many smaller sub-units bonded together. • What is a monomer? • A monomer is a sub-unit of a polymer. A. Making and Breaking Polymers • How are covalent linkages between monomers formed in the creation of organic polymers? • Condensation or dehydration synthesis reactions. • Monomers are covalently linked to one another through the removal of water. Condensation Synthesis Hydrolysis 1. Structure of Monosaccharides • Classified according to the size of their carbon chains, varies from 3 to 7 carbons. Triose = 3 carbons Pentose = 5 carbons Hexose = 6 carbons • In aqueous solutions many monosaccharides form rings: 2. Structure of Disaccharides • Double sugar that consists of 2 monosaccharides, joined by a glycosidic linkage. • What reaction forms the glycosidic linkage? Examples of Disaccharides: Lactose = glucose + galactose Sucrose = glucose + fructose 3. Polysaccharides • Structure: Polymers of a few hundred or a few thousand monosaccharides. • Functions: energy storage molecules or for structural support: B. Lipids • Structure: Greasy or oily nonpolar compounds that are insoluble in water • Functions: 1. Structure of Fatty Acids • Long chains of mostly carbon and hydrogen atoms with a COOH group at one end. • When they are part of lipids, the fatty acids resemble long flexible tails. Saturated and Unsaturated Fats • Unsaturated fats : • Saturated fats: Saturated fatty acid Saturated fatty acid Unsaturated fatty acid 2. Structure of Triglycerides • Glycerol + 3 fatty acids • 3 ester linkages are formed between a hydroxyl group of the glycerol and a carboxyl group of the fatty acid. 3. Phospholipids • Structure: Glycerol + 2 fatty acids + phosphate group. Phospholipids in Water 4. Waxes • Function: • Lipids that serve as coatings for plant parts and as animal coverings. 5. Steroids • Structure: Four carbon rings with no fatty acid tails • Functions: • Component of animal cell membranes • Modified to form sex hormones C. Proteins • Structure: made of C.H.O, +N. • Polypeptide chains • Consist of peptide bonds between 20 possible amino acid monomers • Have a 3 dimensional globular shape 1. Functions of Proteins 2. Structure of Amino Acid Monomers Properties of Amino Acids • Grouped by polarity • Variable R groups (side chains) confer different properties to each amino acid: 3. Primary Structure • Unique sequence of amino acids in a protein • Slight change in primary structure can alter function • Condensation synthesis reactions form the peptide bonds between amino acids 4. Secondary Structure • Repeated folding of protein’s polypeptide backbone • stabilized by H bonds between peptide linkages in the protein’s backbone • 2 types, alpha helix, beta pleated sheets 5. Tertiary Structure • Irregular contortions of a protein due to bonding between R groups • Weak bonds: –H bonding between polar side chains –ionic bonding between charged side chains –hydrophobic and van der Waals interactions Strong Bonds: Disulfide bridges form strong covalent linkages 5. Quaternary Structure • Results from interactions among 2 or more polypeptides Factors That Determine Protein Conformation • Occurs during protein synthesis within cell • Depends on physical conditions of environment –pH, temperature, salinity, etc. • Change in environment may lead to denaturation of protein • Denatured protein is biologically inactive • Can renature if primary structure is not lost D. Nucleic Acids • Two kinds: –DNA: double stranded makes up genes which code for proteins –RNA: functions in actual synthesis of proteins coded for by DNA is made from the DNA 1. Nucleotide Monomer Structure • Both DNA and RNA are composed of nucleotide monomers. • Nucleotide = 5 carbon sugar, phosphate, and nitrogenous base Deoxyribose in DNA Ribose in RNA 2. Building the Polymer • Phosphate group of one nucleotide forms strong covalent bond with the #3 carbon of the sugar of the other nucleotide. 3. Functions of Nucleotides • Monomers for Nucleic Acids • Transfer chemical energy from one molecule to another (e.g. ATP) Summary of the Organic Molecules: