Carbon Compounds Read lesson title aloud to students.

Learning Objectives Describe the unique qualities of carbon. Describe the structures and functions of each of the four groups of macromolecules. Click to reveal each of the learning objectives. Ask students to name compounds they know that contain carbon. As they make suggestions, create a class list on the board. Use their list to start a discussion on the wide variety of carbon compounds that exist in nature.

The Chemistry of Carbon Click to highlight a covalent bond. Explain to students that the lines on the image indicate covalent bonds. Click to highlight double and triple bonds. Explain that these involve sharing two or three pairs of electrons. Ask: How many covalent bonds does carbon form? Click to reveal answer: four (be sure that students understand how double and triple bonds are counted). Discuss the variety of structural arrangements that result from carbon’s ability to form 4 bonds. Click to reveal labels: chain, ring, branching chain Chain Ring Branching chain

Macromolecules Macromolecules are large organic molecules found in living things. Monomers Explain that macromolecules are large organic molecules found in living things that are built by polymerization. Click to reveal the polymerization process. Discuss the polymerization process. Define the terms monomer and polymer, including a discussion of the roots “mono” (single) and “poly” (many). Click to reveal write-on lines. Ask students to identify the components on the image as monomers or polymers. Ask volunteers to answer the question verbally or by writing the correct answer on the board. Click to reveal the answers. You may wish to connect to chemistry by explaining that polymerization commonly occurs in one of two ways: addition polymerization or condensation polymerization. Explain that in addition polymerization, monomers join together without any change in their molecules. In condensation polymerization, a small molecule―often a water molecule―is released. Next, write the molecular formulas for glucose (C6H12O6) and sucrose on the board (C12H22O11). Ask: Is carbohydrate polymerization an example of addition or condensation polymerization? Answer: condensation polymerization You may wish to draw a sketch of this process on the board. Ask: Condensation reactions are sometimes known as dehydration reactions. Why? Answer: A water molecule is lost. Dehydration means the loss of water. You may want to sketch this process on the board. Explain that dehydration and hydrolysis reactions are extremely common in biochemical processes. Polymer

Carbohydrates Living things use carbohydrates as sources of energy and for structural purposes. Discuss the overall structure of carbohydrates (they are made of carbon, hydrogen, and oxygen in a 1:2:1 ratio). Discuss the functions of carbohydrates. Click to reveal two write-on lines. Ask: Which image is of a monomer and which is of a polymer? Ask volunteers to answer the question verbally or by writing the correct answer on the board. Click to reveal both answers. Click to reveal monosaccharide and polysaccharide labels; discuss these terms. Ask: Some carbohydrates are classified as disaccharides. What does this term mean? Answer: These are made of two sugar rings. Explain that monosaccharides and disaccharides are often called simple sugars. Discuss where the monosaccharides glucose and fructose are found. Discuss where the disaccharides sucrose and lactose are found. Explain that polysaccharides can also be called complex carbohydrates. Discuss the functions of glycogen, starch, and cellulose. Polymer Monomer Polysaccharide Monosaccharide

Lipids Lipids are a large and varied group of macromolecules that are not generally soluble in water. Unsaturated Discuss the forms and functions of lipids, including fats, oils, waxes, membrane lipids, and steroids. Ask: Lipids are made mostly from carbon and what element? Click to highlight hydrogens. Answer: hydrogen Click to remove oval. Click to highlight the glycerol molecule. Explain that lipids are made of a glycerol molecule combined with fatty acids. Click to highlight the fatty acids. Click to remove arrows. Explain that saturated fatty acids only have single bonds and contain the maximum number of hydrogens; unsaturated have some double bonds and do not contain the maximum number of hydrogens. Click to reveal a write-on line. Ask: Are the fatty acids on the screen saturated or unsaturated? Click to highlight the double bonds and reveal the answer: unsaturated Explain that unsaturated fatty acids tend to be liquid at room temperature, while saturated are solid.

Nucleic Acids Nucleic acids are polymers made of nucleotide monomers. Nitrogenous base Phosphate group Click to reveal and discuss each component of the nucleotide: 5-carbon sugar, phosphate group, and nitrogenous base. Explain that some nucleotides (such as ATP) have important functions in capturing and transferring chemical energy. Explain that nucleotides can be joined by covalent bonds to form a nucleic acid. Discuss the structure and function of DNA and RNA. 5-carbon sugar

Proteins Proteins are polymers made of amino acid monomers. Amino group: - NH2 Carboxyl group: - COOH Amino group Carboxyl group Peptide bond Explain that proteins are made of amino acids and that amino acids are molecules with an amino group on one end and a carboxyl group at the other end. Click to reveal the structures of an amino group and a carboxyl group, along with two write-on lines. Ask volunteers to identify the amino group and the carboxyl group in the diagram. Have students answer either verbally or by writing the label of each group on the board. Click to reveal both answers. Click to reveal a diagram of how peptide bonds are formed. Explain that amino acids are linked by covalent bonds called peptide bonds. Ask volunteers to circle the peptide bond on the board. Click to reveal the answer.

Protein Structure A protein is a functional molecule built from one or more polypeptides. Explain that proteins are one or more chains of amino acids folded into a functional shape. Explain that there are more than 20 different amino acids found in nature and that proteins are among the most diverse biomolecules. Discuss some of the functions of proteins. Discuss the levels of organization of proteins, from primary to quaternary.

Making Models Make a three-dimensional model of a nucleic acid or a protein. Include a key of your model showing what each part represents. Nitrogenous base Phosphate group Challenge individual students or groups of students to use materials of their choice to create a three-dimensional model of a nucleic acid or a protein. Tell students to make a key for their model showing what each part represents. Have students display their models in the classroom. Click to reveal diagrams of a nucleotide and protein. 5-carbon sugar