Ch 5 - The Structure and Function of Large Biological Molecules

Chapter 5: The Structure and Function of Large Biological Molecules Concept 5.1 Macromolecules are polymers, built from monomers 1. The large molecules of all living things fall into just four main classes. Name them. 2. Circle the three classes that are called macromolecules. Define macromolecule. 3. What is a polymer? Carbohydrates, Lipids, Proteins, Nucleic Acids Carbohydrates, Proteins, Nucleic Acids; Macromolecules are extremely large on the molecular scale, sometimes consisting of thousands of atoms. a monomer? 4. 5. A polymer is a long chain-like molecule, consisting of many similar or identical building blocks linked by covalent bonds. A monomer is a smaller molecule that serves as the building blocks of polymers. Monomers are connected in what type of reaction? What occurs in this reaction? Dehydration joins monomers. By combining two monomer molecules, a water molecule is lost. Each monomer contributes to the reaction's water release. Monomers are added one by one to form polymers. Large molecules (polymers) are converted to monomers in what type of reaction? Polymers are disassembled to monomers by hydrolysis, a process that is essentially the reverse of the dehydration reaction. 6. 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? hydroÐ water lysis 7. break Consider the following reaction: C6H12O6 + C6H12O6 C12H22O11 + H2O a. The equation is not balanced; it is missing a molecule of water. Write it in on the correct side of the equation. b. So, what kind of reaction is this? c. Is C6H12O6 (glucose) a monomer, or a polymer? d. water To summarize, when two monomers are joined, a molecule of __________ is always removed. Dehydration synthesis Monomer Concept 5.2 Carbohydrates serve as fuel and building material 8. LetÕs look at carbohydrates, which include sugars and starches. First, what are the monomers of all carbohydrates? Monosaccharides, or simple sugars 9. 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 pentaÐ, meaning 5.) What is the formula of a hexose sugar? C6H12O6 10. Here are the three hexose sugars. Label each of them. Notice that all sugars have the same two functional groups. Name them: carbonyl group C=O ___________________ hydroxyl group ÑOH ___________________ 11. What is the difference between an aldehyde sugar and a ketone sugar? Depending on the location of the carbonyl group, a sugar is either an aldose (aldehyde sugar) or a ketose (ketone sugar). Glucose, for example, is an aldose; fructose, an isomer of glucose, is a ketose. In aldehyde sugars, the carbonyl group is at the end of the carbon skeleton, while in the ketone sugars, the carbonyl group is within the carbon skeleton. 12. So, as a quick review, all of these sugars have the same chemical formula: C6H12O6. What term did you learn in Chapter 3 for compounds that have the same molecular formulas but different structural formulas? Isomers 13. Here is the abbreviated ring structure of glucose. Where are all the carbons? Each corner represents a carbon; each carbon in this Þgure is labeled 1 through 6. Pay attention to the numbering system. This will be important as we progress in our study. Circle the number 3 carbon. Put a square around the number 5 carbon. 14. LetÕs look at our reaction in question 7 again: C6H12O6 + C6H12O6 C12H22O11 + H2O Notice that two monomers are joined to make a polymer. Since the monomers are monosaccharides, the polymer is a disaccharide. Three disaccharides are important to us with the formula C12H22O11. Name them below and fill out the chart. Disaccharide Formed from which two monosaccharides? Maltose Glucose and glucose Sucrose Glucose and fructose Lactose Glucose and galactose Found where? Malt sugar used in brewing beer Table sugar Milk sugar 15. Have you noticed that all the sugars end in Ðose? This root word means ____________. 16. What is a glycosidic linkage? A glycoside linkage is a covalent bond formed between two monosaccharides by a dehydration reaction. 17. Here is a molecule of starch, which shows 1Ð4 glycosidic linkages. Translate and explain this terminology in terms of carbon numbering. When glucose forms a ring, the hydroxyl group attached to the number 1 carbon is positioned either below or above the plane of the ring. These two ring forms for glucose are called alpha and beta. In starch, all the glucose monomers are in the alpha conÞguration. 18. There are two categories of polysaccharides. Name them and give examples. Type of Polysaccharide Examples Storage Starch, glycogen Structural Cellulose, chitin 19. Why can you not digest cellulose? What organisms can? Humans cannot digest cellulose because they lack the enzyme that can hydrolyze its beta linkages. Humans do posses enzymes that digest starch by hydrolyzing its alpha linkages; however, these enzymes cannot hydrolyze the beta linkages of cellulose because of the distinctly different shapes of these two molecules. 20. LetÕs review some key points about the carbohydrates. Each prompt below describes a unique carbohydrate. Name the correct carbohydrate for each. starch a. Has 1Ð4 B glucose linkages glycogen b. Is a storage polysaccharide produced by vertebrates; stored in your liver glucose c. Two monomers of this form maltose fructose d. Glucose +________ fructose form sucrose fructose e. Monosaccharide commonly called Òfruit sugarÓ lactose f. ÒMilk sugarÓ chitin g. Structural polysaccharide that gives cockroaches their crunch maltose h. Malt sugar; used to brew beer cellulose i. Structural polysaccharide that comprises plant cell walls Concept 5.3 Lipids are a diverse group of hydrophobic molecules 21. Lipids include fats, waxes, oils, phospholipids, and steroids. What characteristic do all lipids share? All lipids mix poorly, if at all, with water. 22. What are the building blocks of fats? Label them on this figure. Fatty acid Glycerol Fatty acid Fatty acid Ester linkage 23. If a fat is composed of 3 fatty acids and 1 glycerol molecule, how many water molecules will be removed to form it? Again, what is this process called? One water molecule is removed for each fatty acid joined to the glycerol, equaling three water molecules for every triacylglycerol formed. This process is called dehydration synthesis. 24. On the figure with question 22, label the ester linkages. 25. Draw a fatty acid chain that is 8 carbons long and is unsaturated. Circle the element in your chain that makes it unsaturated, and explain what this means. Unsaturated fatty acids have one or more double bond, with one fewer hydrogen atom on each double bonded carbon. Nearly all double bonds in naturally occurring fatty acids are cis bonds, which cause a kink in the hydrocarbon chain whenever they occur. 26. Name two saturated fats. butter and most animal fats. 27. Name two unsaturated fats. Olive oil and most plant or Þsh fats. 28. Why are many unsaturated fats liquid at room temperature? The kinks where the cis bonds are located prevent the molecules from packing together closely enough to solidify at room temperature. 29. What is a trans fat? Why should you limit them in your diet? Trans fats are unsaturated fats formed by hydrogenating vegetable oils to prevent lipid separation. Trans fats should be avoided because they promote atherosclerosis, a disease of the blood vessel walls. 30. List four important functions of fats. Energy storage, long-term food reserve in mammals, adipose tissue cushions vital organs, body insulation. 31. Here is a figure that shows the structure of a phospholipid. Label the sketch to show the phosphate group, the glycerol, and the fatty acid chains. Also indicate the region that is hydrophobic and the region that is hydrophilic. phosphate group glycerol hydrophilic hydrophobic fatty acid chains 32. Why is the ÒtailÓ hydrophobic? 33. Which of the two fatty acid chains in the figure with question 31 is unsaturated? Label it. How do you know it is unsaturated? The fatty acid chain on the right is unsaturated. We know this because of the kink in the chain, indicating a double bond. 34. 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 hydrophilc heads, hydrophobic tails, and location of water. water hydrophobic Hydrophilic 35. Study your sketch. Why are the tails all located in the interior? 36. Some people refer to this structure as three hexagons and a doghouse. What is it? The tails are in contact with each other and remote from water because they are hydrophobic. Cholesterol, a steroid 37. What are other examples of steroids? Possible examples include vertebrate sex hormones. Concept 5.4 Proteins have many structures, resulting in a wide range of functions 38. Table 5.1 is loaded with important information. Select any five types of proteins and summarize each type here. Type of Protein Function Example