Chapter 5: The Structure and Function of Large Biological Molecules

Transcription

1 Chapter 5: The Structure and Function of Large Biological Molecules 1. Name the four main classes of organic molecules found in all living things. Which of the four are classified as macromolecules. Define macromolecule. 2. What is a polymer? What is a monomer? Provide a specific example. 3. Monomers are connected in what type of reaction? What occurs in this reaction? 4. Polymers are converted to monomers in what type of reaction? 5. The root words of hydrolysis will be used many times to form other words you will learn this year. What does each root word mean?

2 6. Consider the following reaction: C6H12O6 + C6H12O6 à C12H22O11 a. The equation is not balanced; it is missing a molecule of water. Write it in on the correct side of the equation. b. Polymers are assembled and broken down in two types of reactions: dehydration synthesis and hydrolysis. Which kind of reaction is this? c. Is C6H12O6 (glucose) a monomer, or a polymer? d. To summarize, when two monomers are joined, a molecule of is always removed. 7. What are the monomers of all carbohydrates? 8. Most monosaccharides are some multiple of CH2O. For example, ribose is a 5- carbon sugar with the formula C5H10O5. It is a pentose sugar. (From the root penta, meaning five.) What is the formula of a hexose sugar? 9. Here are the three hexose sugars. Label each of them. Notice that all sugars have the same two functional groups. Name them. 10. As a quick review, all of the sugars in the figure above have the same chemical formula: C6H12O6. IMPORTANT: Change the structure, change the function! What term did you learn in Chapter 4 for compounds that have the same molecular formulas but different structural formulas?

3 11. Here is the abbreviated ring structure of glucose: Where are all the carbons? Number them. Circle the number 3 carbon. Put a square around the number 5 carbon. Is this alpha glucose or beta glucose? Why? 12. What is a disaccharide? Three disaccharides have the formula C12H22O11. Name them below and complete the chart. Disaccharide Formed from Which Two Monosaccharides? Found Where? 13. Have you noticed that all the sugars end in ose? This root word means. 14. What is a glycosidic linkage? 15. Here is a molecule of starch, which shows 1 4 glycosidic linkages of α- glucose monomers as well as 1 6 glycosidic linkages. Number the carbons in the first two sugars of this figure. Use this to explain what is meant by a 1 4 glycosidic linkage.

4 16. There are two categories of polysaccharides. Name them and give examples. Type of Polysaccharide Examples 17. Why can you not digest cellulose? What organisms can? 18. Name the correct carbohydrate for each of the following: Has 1 4 β glucose linkages A storage polysaccharide made by vertebrates; stored in your liver Two monomers of this form maltose Glucose + form sucrose Monosaccharide commonly called fruit sugar Milk sugar Structural polysaccharide that gives cockroaches their crunch Malt sugar; used to brew beer Structural polysaccharide that comprises plant cell walls 19. Lipids include fats, waxes, oils, phospholipids, and steroids. What characteristic do all lipids share? 20. What are the building blocks of fats? Label them on this figure. Label the ester linkages as well.

5 21. If a fat is composed of three fatty acids and one glycerol molecule, how many water molecules will be removed to form it? What is this process called? 22. Draw a fatty acid chain that is eight carbons long and is unsaturated. Circle the element in your chain that makes it unsaturated, and explain what this means. 23. Provide examples of both saturated fats and unsaturated fats. 24. Why are many unsaturated fats liquid at room temperature? 25. What is a trans fat? Why should you limit them in your diet? 26. List four important functions of fats.

6 27. Carefully examine the figure below of a phospholipid and complete the following: Label the sketch to show the phosphate group, the glycerol, and the fatty acid chains. Indicate the region that is hydrophobic and the region that is hydrophilic. Why are the tails hydrophobic? Which of the two fatty acid chains is unsaturated? Label it. How do you know it is unsaturated? 28. To summarize, a phospholipid has a glycerol attached to a phosphate group and two fatty acid chains. The head is hydrophilic, and the tail is hydrophobic. Now, sketch the phospholipid bilayer structure of a plasma membrane. Label the hydrophilic heads, hydrophobic tails, and location of water. 29. Why are the phospholipid tails all located in the interior of your plasma membrane?

7 30. Some people refer to the structure shown in a cholesterol molecule as three hexagons and a doghouse. Cholesterol and other steroids all have this general shape. Name two other steroids. 31. Complete the following table summarizing protein functions. The 1 st has been done for you! Type of Protein Function Example Enzyme Selective acceleration of chemical reactions. Digestive enzymes such as amylase; Enzyme (Catalase) that breaks down H2O2 into H2O and O2

8 32. The monomers of proteins are amino acids. Sketch an amino acid below. Label the alpha (central) carbon, amino group, carboxyl group, and R group. What is represented by R? How many are there? STUDY the 20 different amino acid models. Do you understand why some R groups are nonpolar, some polar, and others electrically charged (acidic or basic)? If you were given an R group, could you place it in the correct group? 33. Define the following terms: ü Peptide bond ü Dipeptide ü Polypeptide ü Dehydration synthesis: 34. Examine the figure to the right. Label the following: ü peptide bond ü H20 ü alpha carbon ü amino group ü carboxyl group ü R group. What process is this figure modeling?

9 35. There are four levels of protein structure. Summarize each level in the following table. Level of Protein Structure Explanation Primary Secondary α helix β pleated sheet Tertiary Quaternary 36. Label each of the levels of protein structure on this figure.

10 37. Enzymes are globular proteins that exhibit at least tertiary structure. Use the figure below to identify and explain each interaction that folds this protein fragment. 38. A very important concept in Biology is a change in structure will change the function. Explain how this principle applies to sickle- cell disease. Why is the structure changed? 39. Besides mutation, which changes the primary structure of a protein, protein structure can be changed by denaturation. Define denaturation, and give at least three ways a protein may become denatured. 40. Chaperone proteins or chaperonins assist in the proper folding of proteins. Annotate the figure below to explain the process.

11 41. The flow of genetic information is from DNA à RNAà protein. Use the figure below to briefly explain the process. Label the nucleus, DNA, mrna, ribosome, amino acids, polypeptide, and cytoplasm. 42. DNA and RNA are nucleic acids. A nucleic acid is composed of nucleotides. The components of a nucleotide are a 5- carbon sugar, a nitrogenous base, and a phosphate group. Carefully STUDY the figure below. Circle the four nucleotides of the polynucleotide strand. Label each nitrogenous base (on the right upper side of figure) and indicate which are purines and which are pyrimidines. Label deoxyribose and ribose (on the right lower side of figure). Label the end of the polynucleotide strand that has a phosphate attached to a 5' carbon 5' Label the other end of the chain which has a hydroxyl group on a 3' carbon 3'. Label the three components of one nucleotide.

12 43. Notice that there are five nitrogen bases. Which four are found in DNA? Which four are found in RNA? 44. How do ribose and deoxyribose sugars differ? 45. Examine and label the model of DNA that was proposed by James Watson and Francis Crick. What is this shape called? Why are the strands said to be antiparallel? What two molecules make up the uprights? What molecules make up the rungs? In a DNA double helix, a region along one DNA strand has the sequence of nitrogenous bases shown below. Write the complementary strand. Indicate the 5' and 3' ends of the new strand. 5'- T A G G C C T- 3' 46. Our current understanding of many areas of biology has been transformed by genomics and proteomics. Explain each, and give an example of its application. 47. Why can DNA and protein sequences serve as tape measures of evolution?