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Molecules of Life. Chapter 3 Part 1. Impacts, Issues: Fear of Frying. Trans fats in hydrogenated vegetable oil raise levels of cholesterol in our blood more than any other fat, and directly alter blood vessel function. Organic Molecules. All molecules of life are built with carbon atoms
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Molecules of Life Chapter 3 Part 1
Impacts, Issues:Fear of Frying • Trans fats in hydrogenated vegetable oil raise levels of cholesterol in our blood more than any other fat, and directly alter blood vessel function
Organic Molecules • All molecules of life are built with carbon atoms • We can use different models to highlight different aspects of the same molecule
3.1 Carbon – The Stuff of Life • Organicmolecules are complex molecules of life, built on a framework of carbon atoms • Carbohydrates • Lipids • Proteins • Nucleic acids
Carbon – The Stuff of Life • Carbon atoms can be assembled and remodeled into many organic compounds • Can bond with one, two, three, or four atoms • Can form polar or nonpolar bonds • Can form chains or rings
Representing Structures of Organic Molecules • Structural model of an organic molecule • Each line is a covalent bond; two lines are double bonds; three lines are triple bonds
Representing Structures of Organic Molecules • Carbon ring structures are represented as polygons; carbon atoms are implied
Representing Structures of Organic Molecules • Ball-and-stick models show positions of atoms in three dimensions; elements are coded by color
Representing Structures of Organic Molecules • Space-filling models show how atoms sharing electrons overlap
red blood cell Fig. 3-3 (top), p. 37
A A space-filling model of hemoglobin shows the complexity of the molecule. Fig. 3-3a, p. 37
B A surface model of the same molecule reveals crevices and folds that are important for its function. Heme groups, in red, are cradled in pockets of the molecule. Fig. 3-3b, p. 37
C A ribbon model of hemoglobin shows all four heme groups, also in red, held in place by the molecule’s coils. Fig. 3-3c, p. 37
3.2 From Structure to Function • The function of organic molecules in biological systems begins with their structure • The building blocks of carbohydrates, lipids, proteins, and nucleic acids bond together in different arrangements to form different kinds of complex molecules
Functional Groups • Hydrocarbon • An organic molecule that consists only of hydrogen and carbon atoms • Most biological molecules have at least one functional group • A cluster of atoms that imparts specific chemical properties to a molecule (polarity, acidity)
Stepped Art Fig. 3-4, p. 38
one of the estrogens testosterone Fig. 3-5a, p. 38
female wood duck male wood duck Fig. 3-5b, p. 38
What Cells Do to Organic Compounds • Metabolism • Activities by which cells acquire and use energy to construct, rearrange, and split organic molecules • Allows cells to live, grow, and reproduce • Requires enzymes (proteins that increase the speed of reactions)
What Cells Do to Organic Compounds • Condensation • Covalent bonding of two molecules to form a larger molecule • Water forms as a product • Hydrolysis • The reverse of condensation • Cleavage reactions split larger molecules into smaller ones • Water is split
What Cells Do to Organic Compounds • Monomers • Molecules used as subunits to build larger molecules (polymers) • Polymers • Larger molecules that are chains of monomers • May be split and used for energy
A) Condensation. An —OH group from one molecule combines with an H atom from another. Water forms as the two molecules bond covalently. B) Hydrolysis. A molecule splits, then an —OH group and an H atom from a water molecule become attached to sites exposed by the reaction. Stepped Art Fig. 3-6, p. 39
3.1-3.2 Key Concepts:Structure Dictates Function • We define cells partly by their capacity to build complex carbohydrates and lipids, proteins, and nucleic acids • All of these organic compounds have functional groups attached to a backbone of carbon atoms
3.3 Carbohydrates • Carbohydrates are the most plentiful biological molecules in the biosphere • Cells use some carbohydrates as structural materials; others for stored or instant energy
Carbohydrates • Carbohydrates • Organic molecules that consist of carbon, hydrogen, and oxygen in a 1:2:1 ratio • Three types of carbohydrates in living systems • Monosaccharides • Oligosaccharides • Polysaccharides
Simple Sugars • Monosaccharides (one sugar unit) are the simplest carbohydrates • Used as an energy source or structural material • Backbones of 5 or 6 carbons • Example: glucose
Short-Chain Carbohydrates • Oligosaccharides • Short chains of monosaccharides • Example: sucrose, a disaccharide
glucose + fructose sucrose + water Fig. 3-7b, p. 40
glucose + fructose sucrose + water Stepped Art Fig. 3-7b, p. 40
Complex Carbohydrates • Polysaccharides • Straight or branched chains of many sugar monomers • The most common polysaccharides are cellulose, starch, and glycogen • All consist of glucose monomers • Each has a different pattern of covalent bonding, and different chemical properties
Chitin • Chitin • A nitrogen-containing polysaccharide that strengthens hard parts of animals such as crabs, and cell walls of fungi
3.3 Key Concepts:Carbohydrates • Carbohydrates are the most abundant biological molecules • They function as energy reservoirs and structural materials • Different types of complex carbohydrates are built from the same subunits of simple sugars, bonded in different patterns
3.4 Greasy, Oily – Must Be Lipids • Lipids function as the body’s major energy reservoir, and as the structural foundation of cell membranes • Lipids • Fatty, oily, or waxy organic compounds that are insoluble in water
Fatty Acids • Many lipids incorporate fatty acids • Simple organic compounds with a carboxyl group joined to a backbone of 4 to 36 carbon atoms • Essential fatty acids are not made by the body and must come from food • Omega-3 and omega-6 fatty acids
Fatty Acids • Saturated, monounsaturated, polyunsaturated
