Activity Handout for Macromolecules - Station 1. Developed by Dr. Greg Perrier ACTIVITY MACROMOLECULES. Introduction

Transcription

1 Activity Handout for Macromolecules - Station 1 Developed by Dr. Greg Perrier ACTIVITY MACROMOLECULES Introduction In this exercise you will learn about the different functional groups that are added onto carbon chains to make organic molecules and about the four major types of macromolecules found in cells: protein, carbohydrates (polysaccharides), lipids, and nucleic acids. The exercise ends with an examination of the chemical tests used to determine the presence of these macromolecules. Station 1 is divided into 3 parts. On the left are the different functional groups. In the middle are the four different types of macromolecules, and on the right are the chemical test used to determine the presence of these macromolecules. I suggest you first read the questions at the end of this worksheet so you know what answers you are looking for. Functional groups First look at the functional groups on the left side of Station 1. Organic molecules are made up of a chain of carbon atoms. Carbon atoms can form 4 bonds. The carbon atoms in the chain form a bond to each of the carbon atoms next to it in the chain, but this leaves 2 remaining bonds. Often one or more hydrogen atoms bond to the carbon, but other small molecules (functional groups) can also bond to the carbon. They type of functional groups that bond to the carbon chain determine what the molecule is. For example, if an amino functional group and a carboxyl (acid) functional group bond to the end of the carbon chain the molecule is an amino acid. Left click on the sign that reads Functional Groups. In the box that appears, select accept and you will be given a notecard. A notecard is just some written information on a topic. Read the notecard on functional groups. Use the same process to open the notecards associated with each functional group by left clicking on the model. Note that the chemical formula (e.g. NH2) is over each functional group. Use the chemical formal and the structure of the molecule with colored balls, to determine which elements (Hydrogen H, Carbon C, Oxygen O, and Nitrogen N) are represented by which colored ball. For example, if the formula in NH2 and the model shows one blue ball and two white balls, then you know the two white balls are H. Once you have determined the colors in the models for the four different types of atoms, go to the question pages of this worksheet and answer question 1.

2 Macromolecules Along the back wall of the kiosk are four boxes labeled: proteins, carbohydrates, lipids, and nucleotides. These are the names of the four types of macromolecules that make up living organisms. For each of these four types of macromolecules there are several to many different specific of molecules. For example, there are thousands of different types of proteins. Proteins Proteins a made of a long chain of amino acids. Left click on the box labeled Proteins and obtain and read the associated notecard, just like you did for the functional groups. Click on the underlined term 20 Amino Acids within the notecard to see a box showing all 20 amino acids that are found in humans. You can click on the lower right corner of this box and drag it to the right lower corner of the screen to make the box larger. Go to the last page and answer questions 2 and 3 on proteins. Carbohydrates Left click on the box labeled Carbohydrates and download and read the notecard for carbohydrates. Notice that a glucose molecule appears above the box and is an example of a monosaccharide, which is Latin/Greek for one sugar. In addition, you will notice that three cards appear. They show you the three common forms in which carbohydrates are found: monosaccharides, disaccharides (two monosaccharides), and polysaccharides (a long chain of many monosaccharides). Each card has a notecard associated with it. Download and read the notecard for monosaccharides. Note that monosaccharides have both open chain and ring forms. Download and read the notecard for disaccharides. After a while, the notecards disappear and you will have to download it again if you have not finished reading it. The disaccharides (two sugars) are made of two monosaccharides linked together in a glycosidic bond. The sugar we use for cooking is disaccharide (sucrose) of one glucose and one fructose molecule. Click on the underlined words Glycosidic Linkage to see how these bonds are formed. Click on the underlined works 3 Disaccharides and note what monosaccharides make up sucrose, maltose, and lactose and how sucrose is bonded differently from the other two disaccharides. Download and read the notecard for polysaccharides (many sugars). Click on the underlined word Polysaccharide to see some of the branched and unbranched forms of polysaccharides. Click on the underlined word Starch to see how the glucose monosaccharides of starch are linked with glycosidic bonds and how starch branches. Starch is found in breads, corn, rice, potatoes, etc. and is a major

3 component of people s diet. Note the different uses for polysaccharides. Go to the last page and answer questions 4, 5, 6, and 7 on carbohydrates. Lipids The third box is labeled lipids (fats, oils, etc.). Download the notecard for lipids. A model of a fatty acid appears above the box. Note it is mainly carbon and hydrogen, with almost no oxygen. Additionally, there are three cards in front of the box, one for each of the three types of lipids common in living organisms: triglycerides, phospholipids, and steroids. Click on the triglyceride card and download and read the associated notecard. Triglycerides form the oils and fats that we eat. Note the two types of molecules (3 fatty acids and 1 glycerol) that are combined to make a triglyceride. Click on the Fatty Acids text to see the structure of a fatty acid and the difference between a saturated and unsaturated fatty acid. Note that the carbon atoms in a fatty acid tail usually have two hydrogen atoms attached to them. In a saturated fatty acid all carbons in the tail have two hydrogen atoms attached and are thus saturated with hydrogen. No more hydrogen atoms can be attached. In the unsaturated fatty acids, two or more carbon atoms in the tail have only one hydrogen atom and form a double bond with a neighboring carbon atom. Because hydrogen atoms can be added to those carbon atoms if the C=C double bond is broken, the fatty acid is considered unsaturated with hydrogen. Next click on the Triglyceride text on the triglyceride notecard and see the structure of the triglyceride. Finally, click on the Unsaturated Fat text and compare the structure of a triglyceride with saturated fatty acids to the structure of a triglyceride with unsaturated fatty acids. Now go to the question pages at the end and answer questions 8 and 9. Right click on the phospholipid card next. If the card has disappeared, click on the lipid box again and decline the lipid notecard which you already have. Download and read the notecard associated with the phospholipid card. Note that phospholipids are the molecules that form all membranes in a cell. Click on the Phospholipid CMU text to see the structure of a phospholipid. Click on the Phospholipid bilayer text to see how phospholipids are organized to form cell membranes. Kiosk 5 has a nice model of a cell membrane. Once you have completed this worksheet, go and have a look at this model to get an understanding of how phospholipids form the membrane and how proteins are imbedded in this membrane to provide channels for things to enter and exit the cell. Now go to the question pages at the end and answer questions 10, 11, and 12. Right click on the steroid card next. Download and read the notecard associated with the steroids. Click on the Steroid Nucleus text. Note how all steroids are formed from a structure with four rings. These rings form the nucleus of the steroid on to which functional groups are attached to form the

4 different types of steroids. Next, click on the Cholesterol text to see the structure of cholesterol. Note the special role cholesterol plays in organisms. Then click on the Estrogen-Testosterone text and note how similar these two hormones are in their structure. Note that other common steroids in cells are the hormone cortisone and vitamin D. Now go to the question pages at the end and answer questions 13 and 14. Nucleotides Right click on the box labeled nucleotides and download and read the associated notecard. Four different types of nucleotides combine to form a long nucleotide chain creating a nucleic acid (DNA and RNA). Note the model of a nucleotide over the box. You might have to move to the very right side of the kiosk to see the model clearly because if the protein model under the cell is behind it, it is hard to distinguish the nucleotide from the protein behind it. Note the three parts of this model. The bases all contain nitrogen and are of two types: purines which are formed by two rings and pyrimidines which have only one ring. The model over the box has the purine adenine. Note the two rings. Click on the text trinucleotide and enlarge the image. Note how the phosphate of one nucleotide bonds to the 3 carbon in the ribose (5 carbon) sugar of the next nucleotide to link nucleotides together. Also note how the phosphate is attached to the 5 carbon in the ribose sugar. A molecule made of a base and ribose sugar without the phosphate is called a nucleoside. The nucleoside adenosine is commonly used as an energy molecule in cells by attaching three phosphates to it to form adenosine triphosphate or ATP. Click on the text ATP2 to see a molecule of ATP. Note the three phosphates off to the left (with orange phosphorus atoms and red oxygen atoms), the ribose sugar in the middle, and the nitrogen base off to the right. The blue atoms in the base are nitrogen. Now go to the question pages at the end and answer questions 15 and 16. Test for the presences of macromolecules Along the right wall of the kiosk are four tests for the presences of macromolecules. The first two tests are for different forms of carbohydrates: sugars (monosacchrides and disaccharides) and starch (a polysaccharide). The Benedict s test is for sugars and the Iodine test is for starches. Next is the Biuret test for the presence of proteins. Finally there is the Sudan IV test for the presence of fat. Study the test tubes. Note the (minus) and + (plus) signs over the test tubes. The signs is when there is no macromolecule present. The + sign is when the macromolecule is present. For the Benedict s test, the solution changes color as more sugar is present. So a little sugar present has a + sign while a lot of sugar present has a ++ sign. Study the color differences and go to the question pages at the end and answer questions 17, 18, 19, and 20.

5 Copy the question pages into a separate file and send them to your professor as an attachment to an . Be sure your name and your avatar s name are on the first page of the questions. Finally, stand near the station and use your camera icon on the toolbar at the bottom of your SL screen to take a photo. Do not save the photo (that cost money) but select the option and the photo to your professor. Be sure to type your real name in the title of the so your professor can give you credit for the photo. You re done with this activity. Feel free to look at other stations in the cell area and roam the NOVA Island.