Building Macromolecules

Transcription

1 Building Macromolecules NGSSS: SC.A.912.L.18.1 Describe the basic molecular structures and primary functions of the four major categories of biological macromolecules. (AA) Background: Biological macromolecules are defined as large molecules made up of smaller organic molecules. There are four classes of macromolecules: carbohydrates, lipids, proteins, and nucleic acids. The base elements of carbohydrates and lipids are Carbon (C), Hydrogen (H) and Oxygen (O). Protein is also made up of these base elements but it also contains Nitrogen (N). When viewing the chemical structures of carbohydrates, lipids and proteins you can distinguish proteins from the other two by the presence of N in its chemical structure. Each macromolecule is made up of smaller organic molecules. For carbohydrates and proteins these smaller molecules are known as monomers. These similar or identical monomers are covalently bonded together to create a large polymer molecule. The monomer unit for carbohydrates is a monosaccharide or a simple sugar. When two of these monosaccharides are linked by covalent bonds a disaccharide is created. When several monosaccharides are bonded together a polysaccharide or complex sugar, is created. Polysaccharides are the polymers of carbohydrates. Proteins are made up of monomers called amino acids. There are twenty amino acids and they can be strung together in unique combinations known as polypeptide chains, the polymer unit for proteins. The exception to the monomer/polymer rule is lipids. Lipid base units are not considered monomers. One type of lipid or fat is made up of fatty acids and glycerol molecules in a 3:1 ratio. The bonding of three fatty acids to one glycerol molecule creates a triglyceride. Monomers, or base units are bonded together to create larger molecules via dehydration. This involves the removal of a water molecule at the bonding site. The larger molecule can be broken down by the reverse process, hydrolysis. This occurs when water is added to break the covalent bonds created during dehydration. Carbohydrates have the general molecular formula CH 2 O, and thus were once thought to represent "hydrated carbon". However, the arrangement of atoms in carbohydrates has little to do with water molecules. Starch and cellulose are two common carbohydrates. Both are macromolecules with molecular weights in the hundreds of thousands. Both are polymers (hence "polysaccharides"); that is, each is built from repeating units, monomers, much as a chain is built from its links. The monomers of both starch and cellulose are the same: units of the sugar glucose. Objective: Students will construct the basic components of organic molecular structure. Students will recognize the way macromolecules are put together and discover how smaller molecules are repeated to form polymers. Vocabulary: Macromolecule, Monomer, Polymer, Carbohydrate, Monosaccharide, Disaccharide, Proteins, Amino acids, Lipids, Nucleic acids Biology HSL Page 217

2 Materials (per group): Use different household or food items to represent the different elements o Blueberries= Hydrogen o Red Grapes= Oxygen o Green grapes= Carbon o Radish= Nitrogen o Bonds= wooden toothpicks or dry spaghetti pieces Procedures: 1. Construct each of the following monomers and answer the questions using the information in the explain portion. Each group will submit completed models as a group. Include diagram of molecules as shown on this document. 2. Molecules are 3-dimensional so models cannot be flat! When constructing a functional group (-OH, -COOH, -NH2) put bonds between all the elements!! 3. Create a key in your journal identifying which food represents which element. Refer to this in building your models. 4. Draw all the molecules you create into your journal and answer the corresponding questions for each completely. Construct glucose A. How many atoms of Carbon are there in Glucose? ; Hydrogen? ; Oxygen? B. What is the chemical formula for glucose? C. Glucose is a monomer for what macromolecule? D. What other simple sugar(s) has the same chemical formula as glucose? E. Simple sugars like glucose are called. F. What is the function of carbohydrates for the body? Biology HSL Page 218

3 Construct Glycine A. Draw a BOX around the amino group on this picture. B. Circle the carboxyl group on this picture. C. Glycine is what type of monomer? (Two words) D. Name the 4 things attached to the center carbon in ALL amino acids. i. ii. iii. iv. E. How many amino acids exist? F. What element is found in amino acid that isn t found in simple sugars like glucose or fructose? G. Amino acids join together to make what type of macromolecule? H. What are some of the functions of proteins in the body? (List several) Construct Glycerol A. Place a CIRCLE around a hydroxyl group. Biology HSL Page 219

4 B. Glycerol is one of two molecules that make up a monomer known as C. Besides glycerol, what 3 other molecules make up a triglyceride? D. Glycerol and other organic compounds with an ol ending are called E. Triglycerides are the monomers for what type of macromolecule? F. Give 3 types of lipids and give their function. i. ii. iii. Construct a Fatty acid A. Draw a BOX around the hydrocarbon chain in these pictures. B. Circle the carboxyl group in both pictures. C. Fatty acids are made of long chains of atoms with attached atoms. D. How many bond(s) does each carbon atom have? E. How many bond(s) does each hydrogen have? F. What 3 elements make up fatty acids? Biology HSL Page 220

5 Construct Cytosine A. Cytosine is an example of a nitrogen base found on acids. B. Name the 2 nucleic acids found in organisms. C. List the name for the elements making up cytosine. D. Name the other 3 nitrogen bases found on DNA. E. What nitrogen base is found on RNA but not DNA? Observations/Conclusions: 1. How many valence electrons does each carbon atom have? 2. What gives carbon the ability to form chains that are almost unlimited in length? 3. Many of the molecules in living cells are so large they are called 4. is the process that forms large organic molecules. 5. When two or more join together, a polymer forms. 6. Create a table in which you compare the components and functions of the following macromolecules: carbohydrates, lipids, nucleic acids, and proteins. Biology HSL Page 221

6 Macromolecule Components Functions Carbohydrates Basic Structure and Formula Lipids Nucleic acids Proteins 7. What role does water play in the process of building macromolecules? Why is it such an important component of life? Extension: The Monomers of Macromolecules All key components of every living cell are made of macromolecules. The four kinds of macromolecules are lipids, carbohydrates, nucleic acids, and proteins. Most macromolecules are polymers constructed of many organic molecules called monomers. These molecules represent one level of basic building blocks of life. These monomers, or single molecules, can be joined with other monomers to form larger units (polymers). They can be divided into four groups: 1. carbohydrates (sugars for energy and structure) 2. lipids (fats for membranes and energy storage) 3. nucleic acids (information bearers) 4. proteins (the molecular machines of the cells). Biology HSL Page 222

7 Try to determine some ways of classifying these molecules below into four groups. There may be more than one right answer. Number each molecule 1, 2, 3 or 4. Finally, what different kinds of atoms are present in these molecules? Write the initials of each kind of atom here. Biology HSL Page 223