What are the building blocks of life?

Transcription

1 Why? What are the building blocks of life? From the smallest single-celled organism to the tallest tree, all life depends on the properties and reactions of four classes of organic (carbon-based) compounds carbohydrates, lipids, proteins, and nucleic acids. These organic molecules are the building blocks of all living things, and are responsible for most of the structure and functions of the body, including energy storage, insulation, growth, repair, communication, and transfer of hereditary information. Simple organic molecules can be joined together to form all the essential biological molecules needed for life. Model 1 Carbohydrates and Lipids 1

2 1. Use Model 1 to show which atoms are present in each type of molecule by listing the name and symbol for each atom included. a. Carbohydrates b. Lipids 2. What holds these atoms together within each molecule in the model? 3. Count the number of carbon, hydrogen and oxygen atoms for glucose, galactose and fructose. Glucose Galactose Fructose C H O C H O C H O 4. Compare the number of atoms in #3. Describe the pattern or trend in the number of atoms shared by these carbohydrates. 5. Lipids are a group of molecules with a long-chain carbon backbone, what is the dominant element attached to the carbon backbone? 6. The fatty acid chain of the lipids is often referred to as a hydrocarbon chain. Discuss with your group why the chain is given this name and write a one-sentence definition for a hydrocarbon. Read This! During chemical reactions, the bonds in molecules are continually broken and reformed. To break a bond, energy must be absorbed. When bonds are formed, energy is released. If more energy is released than absorbed during a chemical change, the process can be used as a source of energy. A general rule for processes such as respiration is the more carbon atoms in a molecule, the more energy that molecule can provide to the organism when it is used as food. Conversely, the more oxygen atoms there are in a molecule, the less energy that molecule can provide, however, the easier it can dissolve in water. 7. Which molecule in Model 1 is more likely to be used for energy storage? EXPLAIN your reasoning. 2 Adapted POGIL Activities for High School Biology

3 8. We store excess food in our body either in the form of carbohydrates (in muscles and the liver) or as fat (adipose tissue). When our body needs additional energy it uses the carbohydrate source first as a source of quick energy, then the fat. Why do you think carbohydrates are used as a source of quick energy rather than fat? Use complete sentences and scientific terminology in your response. Model 2 - Proteins 9. Use Model 2 to show which atoms are present in all proteins (amino acids) by listing the name and symbol for each atom included. 10. Describe how these atoms differ from the atoms found in the molecules from model What three structural groups shown do all amino acids have in common? 12. Three amino acids are shown in Model 2, describe how these differ from one another. 3

4 Model 3 Nucleic Acids A nucleotide (Adenosine, in this example) is made of 3 parts. 13. Use Model 3 to show which atoms are present in nucleic acids by listing the name and symbol for each atom included. 14. How do these atoms differ from the atoms found in Models 1 and 2? 15. Identify and list 3 parts that make up a nucleotide. 16. How is the structure of a nucleotide similar to the structures of the molecules in Models 1 and 2? 4 Adapted POGIL Activities for High School Biology

5 Model 4 Building Larger Molecules Using the paperclip to represent a monomer, make a chain of 10 monomers 17. If the single unit in the model is called a monomer, propose a definition for the term polymer? 18. Referring back to Model 3, identify the monomer and polymer of nucleic acids? 5

6 Model 5 Biochemical Reactions 19. What kind of molecules from the prior models are involved in a. Reaction A b. Reaction B 6 Adapted POGIL Activities for High School Biology

7 20. Using the information in Model 5, complete the table below: Reaction A Reactants Products Monomer Polymer Reaction B 21. Each of the reactants in reaction A is a single sugar molecule, also called a monosaccharide. What prefix before saccharide would you use to describe starch? 22. What product do the two reactions in Model 5 have in common? Read This! When sugars are joined together the new bond that forms is a glycosidic bond. When amino acids are joined the new bond that forms is a peptide bond. 23. On the diagrams in Model 5, circle and label the glycosidic and peptide bonds. 24. These reactions are all referred to as dehydration synthesis or condensation reactions. With your group develop an explanation for why these terms are used to describe these reactions. 25. These reactions can also be reversed, breaking the large molecule into its individual molecules. What substance would need to be added in order to reverse the reaction? 26. Lysis means to split or separate. What prefix would you add to lysis to mean separate or split using water? 27. Using your answers to the previous two questions, what word is used to describe the reaction that uses water to break apart a large molecule? 7

8 28. In the previous models, you have investigated the structure of 4 classes of biological molecules that are essential to life. Hypothesize the role that each class plays in the survival of an organism. Class of Molecules Role Carbohydrates Lipids Proteins Nucleic Acids 8 Adapted POGIL Activities for High School Biology