Activity 3.2.1: What Are Macromolecules?IntroductionRecall the food labels you examined earlier.  What information was listed on each of the labels? List below as many of the specific items included on the labels as you can: Why does a typical American meal include meat, vegetables, and rice or potatoes? What nutrients are you getting from each of those foods?  If you don’t eat meat, what do you eat instead? Does that food have the same nutrients as meat?  The foods we eat contain the nutrients and molecules we need to survive. Some of these molecules are used to build our body parts, some are used to drive chemical reactions necessary for life, and others are used as sources of energy. Many of the molecules in our bodies are very large and are made by combining smaller molecules. These very large molecules are called macromolecules. Macromolecules are an interesting and diverse group of organic compounds with a variety of functions. Macro means big or large, and a macromolecule is a large molecule. There are four types of organic macromolecules: proteins, carbohydrates, nucleic acids, and lipids (fats).   Some macromolecules are also polymers. A polymer is a large molecule made of many smaller repeating sub-units linked together. The smaller sub-units are called monomers. The prefix mono means one, and the prefix poly means many. Consequently, a monomer is one of something and a polymer is made of many monomers. The pattern or sequence of the repeating sub-units determines the characteristics of a particular polymer. Proteins, carbohydrates, and nucleic acids are all organic polymers. Lipids are not polymers because they are not composed of a single type of sub-unit. Instead of being constructed of repeating smaller molecules, lipids are aggregates (mixture) of multiple molecules. Lipids are often smaller than the other types of macromolecules. Even though lipids are not polymers and are smaller than the other macromolecules, they are generally considered to be a macromolecule because they can be very large and they are formed by the combination of smaller molecules. Because different lipids are made from different types of molecules, their basic structures are very different. The unifying features of all lipids are that they are primarily composed of hydrogen and carbon atoms and are insoluble in water.  In this activity, you will take a much closer look at the structure of some of the molecules listed on the food labels and begin to develop an understanding of their functions in your body.

Equipment·         Computer with Internet access·         Project Lead The Way Carbohydrates and Fats Model Kit·         Alpha-helix protein model, assembled·         Beta-pleated sheet protein model, assembled·         Atomic Models Student Resource Sheet·         Laboratory Journal or notebook·         Colored pencils

ProcedureAfter you complete this activity, you should be able to:·         Recognize and classify a diagram or model of a macromolecule as a protein, carbohydrate, or lipid.·         Recognize and classify a diagram or model of the sub-units of each macromolecule.·         Explain the functions of each of the macromolecules in the body.·         Explain the processes of dehydration synthesis and hydrolysis. 1.    Work with a partner on this activity. Use colored pencils for all sketches and match as closely as possible the colors in your sketches to the colors of the atoms in the model kits. These should be rough sketches you can use to recall what the model looked like; they do not need to be exact drawings of each model.2.    Read the introductory information about each type of molecule, then read and follow each of the procedural steps. Before writing an answer to any question, discuss your response with your partner and reach agreement on what should be written.

Proteins PART IProteins are large molecules with many different shapes and structures. They are the primary structural component of all tissues in humans and all other animals. Proteins build, maintain, and repair the tissues in your body; they are highly specialized and have specific purposes in your body. For example, the proteins in your muscles allow for movement, and different proteins in your blood carry messages from one cell to another. Proteins are an essential part of your diet. The proteins you eat are broken down by your digestive system into their component parts, and these components are re-assembled into new protein molecules your body can use. Proteins are polymers made of repeating units called amino acids. There are twenty different amino acids. An amino acid consists of an amine group (NH2), a carboxyl group (COOH), and a variable group that determines the identity of the amino acid. The variable group is often referred to as the R group. The bond that holds two amino acids together is called a peptide bond. Short chains of amino acids, generally containing fewer than 50 amino acids, are

referred to as peptides; longer chains of amino acids are referred to as polypeptides. Each protein has its own combination of different amino acids. Proteins vary greatly in shape and function. Proteins are crucial chemicals for all living things. One way they can be classified is by what they do. Generally speaking, they are structural components, signal or communication molecules, enzymes, transport molecules, or hormones. 3.    Go to the Wisconsin Online website and the Biomolecules: Proteins page written by Barbara Liang. Accessed May 12, 2010. Available at: http://www.wisc-online.com/objects/index_tj.asp?objID=AP133044.    Complete the tutorial about proteins. Answer the following questions after reading through the introduction of the activity and completing the tutorial.

A. What are four functions of proteins?

B. Polymers are made of repeating units called ________________.

C. What three components make up proteins?

D. How are the primary and secondary protein structures determined?

E. The shape of a protein determines its function. What are 4 factors that can destroy the shape of a protein?

F. What types of protein molecules contain all 20 amino acids?

5.    Go to the University of Arizona’s Biology Project tutorial on amino acids entitled “The Chemistry of Amino Acids” available at: www.biology.arizona.edu/biochemistry/problem_sets/aa/aa.html.6.    Read through the article about amino acids. Answer the following questions based on the article.

A. How many amino acids can humans produce? How are the other 10 amino acids supplied?

B. Why can plants make all 20 amino acids but humans cannot?

C. Why is it necessary for you to know the structure and chemistry of amino acids?

Import three diagrams of amino acids. Visit the following website for guidance. http://chemistry.about.com/od/imagesclipartstructures/ig/Amino-Acid-Structures/. Find pictures of 3 amino acids online and insert the images below.      

 

7.    Go to the Three Dimensional Structure of a Protein animation located on the Learner.org website as an archived animation. Accessed May 12, 2010 and available at: http://www.learner.org/channel/courses/biology/archive/animations/hires/a_proteo1_h.html.8.    View the animation. Answer the following questions about protein structure after watching the animation:

Describe the different levels of protein structure: Primary

Secondary

Tertiary

Quaternary.

9.    Examine the two models of protein secondary structure, the alpha helix and the beta-pleated sheet. In the spaces below, write brief descriptions of the structures and make simple sketches so you remember what the two forms look like.

Description and Sketch of Alpha-Helix Protein Model            Description and Sketch of Beta-Pleated Sheet Protein Model     

10. Answer Conclusion questions 1 to 3. 

PART B11. Read the section below about lipids.  Be able to explain why the classification of lipids includes more than just fats.LipidsThe term lipid is often misunderstood. Too often the term lipid is equated with the term fat. Actually, fat is only one type of lipid. The lipids classification includes a very diverse group of molecules that are essential for life. All lipids are non-polar (no atomic charges or ions) and hydrophobic (do not dissolve in water); it is those two features that are the basis for classifying a macromolecule as a lipid. Unlike the other macromolecules, lipids do not have a single type of building block. The common structural feature all lipids share is that all lipids are primarily composed of hydrogen and carbon atoms, along with a few oxygen atoms. There are many different types of lipids. Fats and oils, correctly called triglycerides, are one type. Phospholipids, steroids, and fat-soluble vitamins such as A, E, D and K are also lipids. So you can see the term lipid includes many different types of compounds. Lipids have many functions in the body. Some lipids store large quantities of energy. Triglycerides have this role and can be classified as saturated or unsaturated. Other lipids are essential for the structure of membranes (phospholipids), cell communication (steroid hormones), and bone structure (vitamins D). 12. Answer the following questions after reading the intro about lipids:

A. What are 2 characteristics of all lipids?

B. List 4 different types of lipids

C. List 4 functions of lipids

13. Go to the Wisconsin Online website and the Biomolecules: Lipids page written by Barbara Liang. Accessed May 12, 2010 and available at: http://www.wisc-online.com/objects/index_tj.asp?objID=AP13204.14. Complete the following questions:

A. List two differences between saturated and unsaturated fats.

B. Describe the composition of the phospholipid bilayer.

C. What is the structure of a cholesterol molecule? What are 4 functions of cholesterol?

15. Go to the Biology at University of Cincinnati Clermont College webpage on lipids written by J. Stein Carter. Accessed May 12, 2010 and available at http://www.biology.clc.uc.edu/Courses/bio104/lipids.htm.16. Read the information on lipids, oils, waxes, and the structure of fatty acids. Answer the following questions:

A. What is the danger of reusing oil in a frying pan over and over as they do at fast food restaurants.

B. How many calories per gram are present in fats? What about carbohydrates? Proteins?

C. Why can high-carbohydrate weight loss diets work?

D. Describe a couple of reasons as to why cholesterol is not the “bad guy.”

E. Describe the results of the study where people ate an egg a day.

F. What is the difference between LDL and HDL cholesterol?

17. Examine the diagram of a triglyceride located on the right side on the webpage in the section titled Structure of Fatty Acids.18. Notice that a triglyceride is composed of two types of building blocks, a glycerol molecule and three fatty acid molecules. It is because of the three fatty acids that the molecule has the name triglyceride.19. Notice that the glycerol molecule contains three carbon atoms linked to hydrogen and oxygen atoms.20. Import a diagram of a glycerol moleculeGlycerol Molecule        21. Import a picture of a triglyceride molecule from the internet. Be sure the triglyceride looks like the picture from the website you were just on.Picture of Triglyceride Lipid Model        22. Answer Conclusion Questions 4 and 5.23. Read the next section about Carbohydrates. Be able to explain the differences between a monosaccharide, a disaccharide, and a polysaccharide.

PART 3CarbohydratesCarbohydrates are the primary energy molecule for the human body. The body can obtain energy from lipids and proteins, but carbohydrates are used first if they are available. Carbohydrates are easily broken down by the body; as they are broken into smaller and smaller molecules, the energy stored in the carbohydrate molecule is captured and ultimately transferred to another molecule called adenosine tri-phosphate (ATP).  ATP is the actual energy source for all

cell processes including communication, growth, repair, and reproduction. To convert the energy in a carbohydrate molecule to an ATP requires the action of several proteins (enzymes) and oxygen. Similar to lipids, carbohydrates consist of oxygen, hydrogen and carbon atoms.  The difference between the macromolecules is in the ratio of the atoms. Carbohydrates usually have a ratio of 1 carbon: 2 hydrogen: 1 oxygen. Lipids have far fewer oxygen atoms and do not have a consistent ratio of the atoms. Unlike lipids, carbohydrates are polymers. The building block, or monomer, of a carbohydrate is a sugar molecule, also known as a saccharide. How many sugar molecules do you think are in a monosaccharide?___________ How many do you think are in a disaccharide? __________ Read on to see if your predictions are correct.

MonosaccharidesThe simplest carbohydrates are simple sugars which are made of only one monomer and are called monosaccharides. Examples of monosaccharides include glucose, fructose, galactose, deoxyribose and ribose. Glucose is a common sweetener used in foods and is the primary building block of many complex carbohydrates that are essential for our bodies. Fructose is the simple sugar found in many fruits.  Deoxyribose and ribose are the sugar molecules used to form deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) that you will study later in units 4 and 5. 24. Answer the following questions after reading the introduction to carbohydrates above:

A. Why are carbohydrates the preferred fuel source of the body?

B. What is the significance of ATP?

C. What is the building block (monomer) of a carbohydrate?

25. Go to the Western Kentucky University website for Biology 113, Carbohydrates Accessed May 12, 2010 and available at: http://bioweb.wku.edu/courses/BIOL115/Wyatt/Biochem/Carbos.htm.  Note if you click on the red stars, additional information is displayed.Read the information on carbohydrates. Answer the following questions after viewing the website.

A. What is another name for table sugar?

B. What are two examples of polysachharides?

C. Define isomer:

D. What are the primary functions of starch and glycogen?

26. Import a picture of the glucose in the ring formation in the space below. Be sure to label all parts. Picture of Glucose in Ring Formation       Dehydration Synthesis and HydrolysisIn order to combine the subunits of proteins, lipids, and carbohydrates, a process known as dehydration synthesis is used. Without reading further, predict what this term might mean by taking the term apart and thinking about the word dehydration by itself and the word synthesis by itself. 27. Write your prediction of the meaning of the term dehydration synthesis in the space below:Prediction of the Meaning of the Term Dehydration Synthesis   

In order to break a macromolecule apart to use the subunits to make other products or to obtain energy, a process called hydrolysis is used. Without reading further, predict what this term might mean. Take the word apart and consider the meanings the terms of hydro and lysis.  28. Write your prediction of the meaning of the term hydrolysis in the space below.Prediction of the Meaning of the Term Hydrolysis 

 29. Go to the Lone Star College North Harris Biology website to view the page on dehydration synthesis and hydrolysis. Accessed May 12, 2010 and available at: http://nhscience.lonestar.edu/biol//dehydrat/dehydrat.html. Use the dehydration synthesis and hydrolysis buttons for each type of macromolecule to view the animations. Answer the following question:

A. After viewing the following animations describe the difference between hydrolysis and dehydration synthesis.

30. Go to the Western Kentucky University website for Biology 113, Macromolecules (Biochemistry) Accessed May 12, 2010 and available at: http://bioweb.wku.edu/courses/biol115/Wyatt/Biochem/macromolecules.htm.  Note: if you click on the red stars, additional information is displayed.31. Write a definition for dehydration synthesis in the space below.Definition of Dehydration Synthesis   32. Write a definition for hydrolysis in the space below.Definition of Hydrolysis    DisaccharidesTwo monosaccharides can combine to form one new molecule, called a disaccharide. Were your predictions of the meanings of the words monosaccharide and disaccharide accurate? Examples of disaccharides include maltose (two linked glucose molecules), sucrose (glucose linked to fructose), and lactose (glucose linked to galactose). Maltose is a sugar commonly found in seeds and is used to make malted candy (malted milk balls) or drinks (malted milkshake). You may have eaten sucrose

this morning in your coffee or on your cereal; it is common table sugar. If you had milk on your cereal, then you probably ate lactose this morning because it is the sugar found in cow’s milk. If you used soy or rice milk, then you did not eat any lactose because these products do not contain lactose. For that reason they are good alternatives for people who are allergic to cow’s milk or are lactose intolerant. Soy and rice milk are both sweetened during their manufacturing process by the addition of sucrose. 33. Import a picture of a disaccharide. Be sure to label all parts. (Remember the sketch is not meant to be an exact drawing; it is a study tool so you can look at it later and remember what your model looked like.)PIcture of the Disaccharide Maltose      34. Read the next section about polysaccharides. Be able to discuss how polysaccharides are used to store energy liver and muscle cells, and are broken down as needed to provide energy for the body.

PolysaccharidesPolysaccharides contain hundreds or even thousands of monosaccharides linked together by dehydration synthesis to form long chains. These carbohydrates do not taste sweet and are insoluble in water. Animals, including humans, combine multiple glucose molecules to form glycogen which is stored in the liver and muscle tissue for use as an energy source. When energy is needed, the glycogen is broken down into multiple glucose molecules. The glucose molecules are further broken down and the energy stored in the molecule is used to produce ATP, the energy molecule used by all cells.  Plants combine multiple glucose molecules to form a different polysaccharide for energy storage, starch. Humans can digest plant starches found in rice, potatoes, wheat, and corn into their component glucose molecules and use these glucose molecules for energy or to build new carbohydrates. Plants also combine multiple glucose molecules to form the structural polysaccharide, cellulose. Humans can not digest or breakdown cellulose, so it is considered a fiber. 35.  Read the next section about Energy Conversions. Be able to describe how the energy in macromolecules, especially carbohydrates, is captured for use in your bodyEnergy ConversionsThe human body depends upon many chemical reactions occurring at the same time. Synthesis reactions are those that combine atoms or molecules together to make a new product. All synthesis reactions, collectively in the body, are referred

to as anabolism. These reactions absorb more energy than they produce. The creation of glycogen is an example of an anabolistic reaction. The energy of many small molecules is combined into a large one. You may have heard the term anabolic steroids; these are hormones that cause the body to build tissue, especially muscle. That is why some athletes have taken them to gain an unfair advantage. The opposite of anabolism is catabolism. It is the decomposition (or breaking apart) of large molecules into smaller ones. During catabolism, more energy is released than absorbed. The breakdown of a starch molecule into its component glucose molecules is an example of catabolism. During both anabolism and catabolism, an energy exchange occurs. In some instances, one type of molecule is used to store the energy and a different molecule is the actual energy source. To understand this principle better, let’s use an analogy about gasoline. Gasoline is derived from crude oil. Energy is stored in the crude oil, but automobiles do not run on crude oil. The energy in the crude oil molecules is unusable until the oil is refined or processed. The refining breaks down the oil into smaller molecules of gasoline. The gasoline is then burned to provide energy to the engine of the car. Just as crude oil must be broken down into gasoline so it can provide energy to the car, the human body must breakdown food particles into the macromolecules (digestion), then breakdown the macromolecules to obtain energy usable by cells (cellular respiration). After we consume our food, it is digested into its component parts. The preferred macromolecule to use as an energy source is carbohydrate. Carbohydrates are further broken down into their component sugar molecules. Many carbohydrates are formed by linking glucose molecules, so they are broken down into multiple glucose molecules and absorbed into the blood stream from the small intestine. The glucose molecules travel to the body’s cells where a series of chemical reactions, known as cellular respiration, ultimately make adenosine tri-phosphate, ATP. Using the analogy of a car, ATP is the human body’s gasoline. It is the compound that powers all metabolic reactions. Without ATP we would not be alive.

36. After reading about energy conversions above (35) answer the following questions:

A. Define anabolism and give an example of an anabolistic reaction in the body.

B. Define catabolism. Give an example of this type of reaction.

C. What happens during both anabolism and catabolism?

D. Carbohydrates are the body’s preferred fuel source. Describe how the body breaks down carbohydrates into a useable energy source.

Conclusion1.    Explain how it is possible to have thousands of different proteins when there are only 20 different amino acids.      2.    What determines the properties of a specific protein?      3.    Explain what determines each of the different structural levels of a protein (primary, secondary, tertiary, and quaternary) and how the structural levels are different from each other.        

 4.    Why are lipids not considered to be polymers?      

 5.    List three ways the structure of a triglyceride differs from the structure of a protein.         6.    How do monosaccharides, disaccharides and polysaccharides differ in structure?       7.    Sugar dissolves in water. Think back to the interactive PowerPoint on chemistry and the discussion about bonding and polarity. Sugar is not an ionic substance. What kind of bonds must be in this molecule? Explain your answer.     8.    In a chemical reaction the substance of primary importance that is created is referred to as the product and other substances that result are called the by-products. When you linked the two glucose molecules together, what was the product you created? 

 9.    What by-product was produced when you linked the two glucose molecules together?  

10. Explain from a mathematical perspective, how the ratios of the different types of atoms (carbon, hydrogen, and oxygen) vary in the different types of carbohydrates (monosaccharide, disaccharide, and polysaccharide).        

11. Based on what you have now learned about biochemistry, predict which one of the three types of carbohydrates (monosaccharide, disaccharide, or polysaccharide) would have more energy stored in its structure. Explain your answer.       12. Some people might argue that an orange is a high energy food. Others would disagree, and consider a cup of pasta to be a high energy food. How is it possible for both groups of people to argue their position and be correct? Based on the actual biochemistry of the molecules involved, which food has a higher energy content? Explain your answers.         13. Even though lipids and carbohydrates are made from the same elements (carbon, hydrogen, and oxygen), why is it easy to tell them apart when viewing a model of each?      

14. Describe two reasons why having a basic knowledge of biochemistry is important for everyone.