Chapter 5: What are the major types of organic molecules? polymers four major classes of biologically important organic molecules: carbohydrates lipids proteins (and related compounds) nucleic acids (and related compounds) . • Discuss hydrolysis and condensation, and the connection between them. many biological molecules are polymers polymers: long chains w/ repeating subunits (monomers) example: proteins - amino acids example: nucleic acids – nucleotides macromolecules: very large polymers (100s of subunits) . Polymers hydrolysis (“break with water”) . Polymers condensation (dehydration synthesis) . • Discuss hydrolysis and condensation, and the connection between them. Chapter 5: What are the major types of organic molecules? four major classes of biologically important organic molecules: carbohydrates lipids proteins (and related compounds) nucleic acids (and related compounds) . • For each organic molecule class, address what they are (structure) and what they are used for (function). • Carbohydrates: what are they, and what are they used for? • What terms are associated with them (including the monomers and the polymer bond name)? • Give some examples of molecules in this group. Carbohydrates carbohydrates: carbon, hydrogen, and oxygen ratio typically (CH2O)n sugars, starches, and cellulose . Carbohydrates main molecules of life for energy storage; consumed for energy production some used as building materials monosaccharides, disaccharides, and polysaccharides . Carbohydrates monosaccharides single monomer 3, 4, 5, 6, or 7 carbons trioses, tetroses, pentoses, hexoses, and heptoses pentose examples: ribose and deoxyribose hexose examples: glucose, fructose, and galactose . Carbohydrates structural formulas for glucose, fructose, and galactose isomers of each other glucose and galactose are structural isomers of fructose glucose and galactose are diastereomers . Carbohydrates pentose and hexose sugars form ring structures in solution carbons given position numbers . Carbohydrates ring structures in solution often creates diastereomers example: a-glucose and b-glucose . Carbohydrates disaccharides: two monosaccharide units joined by a glycosidic linkage or bond condensation oxygen atom is bound to a carbon from each momomer linkage typically carbon 1 to carbon 4 . Carbohydrates maltose, sucrose, lactose: common disaccharides maltose (malt sugar): two glucose subunits sucrose (table sugar): glucose + fructose lactose (milk sugar): glucose + galactose + . Carbohydrates polysaccharides number of subunits varies, typically thousands can be branched or unbranched some are easily broken down and are good for energy storage (examples: starch, glycogen) some are harder to break down and are good as structural components (example: cellulose) . Carbohydrates starch: main energy storage carbohydrate of plants polymer made from α-glucose units, mostly α1-4 linkages amylose = unbranched starch amylopectin = branched starch (branches usually 1-6 linkages) amyloplasts, a type of plastid for starch storage . Carbohydrates glycogen: main energy storage carbohydrate of animals very highly branched more water-soluble is NOT stored in an organelle mostly found in liver and muscle cells . Carbohydrates cellulose: major structural component plant cell walls b-glucose units similar to starch, but note that the b1-4 linkage makes a huge difference . Carbohydrates unlike starch, most organisms cannot digest cellulose cellulose is a major constituent of cotton, wood, and paper cellulose contains ~50% of the carbon in found in plants . Carbohydrates fibrous cellulose is the “fiber” in your diet some fungi, bacteria, and protozoa make enzymes that can break down cellulose animals that live on materials rich in cellulose, e.g. cattle, sheep and termites, contain microorganisms in their gut that are able to break down cellulose for use by the animal . Carbohydrates carbohydrates can be modified from the basic (CH2O)n formula many modified carbohydrates have important biological roles example: chitin – structural component in fungal cell walls and arthropod exoskeltons example: galactosamine in cartilage example: glycoproteins and glycolipids cellular membranes . • Carbohydrates: what are they, and what are they used for? • What terms are associated with them (including the monomers and the polymer bond name)? • Give some examples of molecules in this group. • Lipids: what are they, and what are they used for? • What terms are associated with them (including majors classes and bond names)? • Give some examples of molecules in this group. Lipids lipids defined by solubility, not structure oily or fatty compounds lipids are principally hydrophobic mainly carbon and hydrogen some do have polar and nonpolar regions some oxygen and/or phosphorus, mainly in polar regions . Lipids roles of lipids include serving as: membrane structural components signaling molecules energy storage molecules . Lipids major classes of lipids that you need to know are: triacylglycerols (fats) phospholipids terpenes and terpenoids . Lipids triacylglycerols: glycerol + 3 fatty acids glycerol: 3C sugar alcohol w/ 3 (-OH) groups fatty acid: long, unbranched hydrocarbon chain w/ (-COOH) at end . Lipids saturated fatty acids: no carbon-carbon double bonds (usually solid at room temp) . Lipids unsaturated fatty acids: one or more double bonds (usually liquid at room temp) monounsaturated – one double bond polyunsaturated – more than one double bond . Lipids about 30 different fatty acids are commonly found in triacylglycerols; most have an even number of carbons . Lipids condensation results in an ester linkage between a fatty acid and the glycerol . Lipids names based on number of attached fatty acids: one = monoacylglycerol two = diacylglycerol three = triacylglycerol . Carboxyl Glycerol Fatty acid (a) Ester linkage Palmitic acid Oleic acid Linoleic acid (b) A triacyglycerol (c) Palmitic (d) Oleic (e) Linoleic . Lipids triacylglycerols (also called triglycerides) are the most abundant lipids, and are important sources of energy . Lipids phospholipids consist of: a diacylglycerol molecule a phosphate group esterified to the third -OH group of glycerol an organic molecule (such as choline) esterified to the phosphate . Lipids phospholipids are amphipathic polar end (the phosphate and organic molecule) nonpolar end (the two fatty acids) this is often drawn with a polar “head” and two nonpolar “tails” . Lipids the nonpolar (or hydrophobic) portion of phospholipids tends to stay away from water the polar (or hydrophilic) portion of the molecule tends to interact with water this, along with shape, causes phospholipids to form bilayers when mixed with water because of this character phospholipids are important constituents of biological membranes . Lipids terpenes are long-chained lipids built from 5-carbon isoprene units many pigments, such as chlorophyll, carotenoids, and retinal, are terpenes or modified terpenes (often called terpenoids) . Lipids other terpenes/terpenoids include natural rubber and “essential oils” such as plant fragrances and many spices . Lipids steroids are terpene derivatives that contain four rings of carbon atoms side chains extend from the rings; length and structure of the side chains varies one type of steroid, cholesterol, is an important component of cell membranes other examples: many hormones such as testosterone, estrogens . • Lipids: what are they, and what are they used for? • What terms are associated with them (including majors classes and bond names)? • Give some examples of molecules in this group. • Polypeptides: what are they, and what are they used for? • What terms are associated with them (including the monomers and the polymer bond name)? • Give some examples of molecules in this group. Proteins (polypeptides) macromolecules formed from amino acid monomers proteins have great structural diversity and perform many roles roles include enzyme catalysis, defense, transport, structure/support, motion, regulation protein structure determines protein function . proteins are polymers made of amino acid monomers linked together by peptide bonds amino acids consist of a central or alpha carbon bound to: a hydrogen atom an amino group (-NH2) a carboxyl group (-COOH) and a variable side chain (R group) . proteins are polymers made of amino acid monomers linked together by peptide bonds the R group determines the identity and much of the chemical properties of the amino acid there are 20 amino acids that commonly occur in proteins pay attention to what makes an R group polar, nonpolar, or ionic (charged) and thus their hydrophobic or hydrophilic nature . • Discuss how to tell which of these categories an amino acid falls into: hydrophobic or hydrophilic (and within the hydrophilic, polar or charged). cysteine and tyrosine are actually essentially nonpolar . Alpha carbon R group POLAR = hydrophilic Asparagine Glutamine Tyrosine Serine Theonine Asn Gln Tyr Ser Thr Exception: mainly hydrophobic ACIDIC BASIC ELECTRICALLY CHARGED= hydrophilic ELECTRICALLY Aspartic Glutamic Acid Arginine Lysine Histidine Asn Glu Arg Lys His Glycine Alanine Valine Leucine Isoleucine Gly Ala Val Leu Ile NONPOLAR NONPOLAR = hydrophobic Tryptophan Proline Cysteine Methionine Phenylalanine Trp Pro Cys Met Phe • Discuss how to tell which of these categories an amino acid falls into: hydrophobic or hydrophilic (and within the hydrophilic, polar or