Study Guides (248,605)
Canada (121,634)
Biology (1,112)
BIOL 130L (41)

Identifying macromolecules lab report

12 Pages
728 Views

Department
Biology
Course Code
BIOL 130L
Professor
Dragana Miskovic

This preview shows pages 1,2 and half of page 3. Sign up to view the full 12 pages of the document.
Description
BIOL 130 Lab Report Identifying Two Macromolecules ­ Carbohydrates and Proteins [Type the company name] INTRODUCTION As the name suggests, macromolecules are large molecules that make up more than 90% of the total cell mass. These biological macromolecules vary greatly in size - from several hundred to several hundred million molecular weight units - and are made up of monomer units. There are four major classes of biological macromolecules: proteins, carbohydrates, lipids, and nucleic acids (Sheeler & Bianchi, 1980). Proteins are made up of polymers of amino acids. The shape and structure of a cell is defined by proteins (Alberts et al., 1989). Carbohydrates are made up of polymers of simple sugars called monosaccharides. Carbohydrates can also be made up of two sugars, three sugars or more, and they are called disaccharides and polysaccharides respectively (Sheeler & Bianchi, 1980). Lipids are a collection of molecules that are insoluble in water but soluble in non polar solvents. Common lipids include fatty acids, glycolipds, neutral fats, and so on (Sheeler & Bianchi, 1980). Nucleic acids store and transfer all kinds of genetic information and are polymers of nucleotides (Pollard & Earnshaw, 2004). The experiment performed was designed to identify the biological macromolecules. These biological macromolecules are to be identified by the changes in colour through three different tests - Iodine Test for starch and glycogen, Benedict's Test for reducing sugars, and Biuret Test for Proteins. However, only two macromolecules are being identified in this experiment - carbohydrates and proteins. There are 12 solutions to be tested in this experiment. The Iodine test is used to indentify starch and glycogen in the given solutions. Of the 12 solutions, solution 8 is a starch solution and solution 7 is a glycogen solution. Starch solutions turn blue-black when Iodine solution is added to it. This is due to the formation of polyiodide chains when the Iodine solution mixes with starch. Starch contains both amylose and amylopectin. The amylose molecules in starch form helices at the locations where the Iodine 2 molecules assemble. This cause a dark blue-black colour change ("Starch-iodine test", 2008). Therefore, solution 8 should turn blue-black when Iodine solution is added to it since it is a starch solution. However, glycogen solutions turn red-brown when Iodine solution is added. The chemical structure of glycogen is similar to the structure of amylopectin. Glycogen is highly branched. These branches are formed through acetal linkages. It is because of the highly branched structure of glycogen that solutions of glycogen turn red-brown in Iodine solutions (Ophardt, 2003). Thus, solution 7, a glycogen solution, should turn red-brown with the addition of Iodine solution. Solution 12 is an unknown, unknown 318. The Benedict's Test is used to identify reducing sugars. Reducing sugars are sugars that contain free aldehyde or ketone groups that are oxidized into carboxylic acids. The Benedict's +2 solution contains blue Cu ions. These ions react with the electrons from aldehyde or ketone group, reducing the Cu ions to Cu ions to form a red-brown precipitate of Copper (I) Oxide (Hunt, n.d.). A change in colour to red-brown indicates the presence of sugars. Of the 12 solutions, solution 4 is a solution of honey. This solution should turn red-brown since honey contains sugars. Solutions 1(glucose solution), 3(maltose solution), 5(sucrose solution), and 6(lactose solution) should turn red-brown as well. This is because glucose, maltose, sucrose, and lactose are sugars. There should be no change in colour in the other solutions. However, since solution 12 is an unknown solution, we do not know if a colour change will take place. The Biuret Test is used to identify the presence of proteins in a solution. During the Biuret Test, 2 mL of 10% NaOH and 5 drops of 1% CuSO solutions are added to every test tube. 4 Proteins are made up of polypeptides of amino acid chains linked together by peptide bonds. The polypeptide backbone includes Nitrogen from the amino group of the amino acid, the α- carbon, and the carbonyl carbon from the carboxyl group (Pollard & Earnshaw, 2004). The 3 CuSO solution contains Cu ions that cause protein solutions to turn violet when they stick to 4 the Nitrogen atoms of the amino group (McRae, n.d.). Of the 12 solutions, solution 9 should turn violet because it was originally a protein solution. However, none of the other solutions should turn violet, and the colour change of the unknown 318 solution cannot be predicted yet. MATERIALS USED Please refer to Biology 130 Lab Manual, Department of Biology 2013, pages 13-14. No other deviations were made from this procedure. METHODSAND PROCEDURE Please refer to Biology 130 Lab Manual, Department of Biology 2013, pages 14-18. No other deviations were made from this procedure. 4 RESULTS Table 1: Observations of the Iodine Test for Starch and Glycogen Test Tube Colour before Colour after Positive/Negative #1 (1% glucose Clear transparent No change(clear Negative solution) transparent) #2 (0.3% glucose-1- Clear transparent No change(clear Negative phosphate) transparent) #3 (1% maltose Clear transparent No change(clear Negative solution) transparent) #4 (honey solution) Slightly translucent No change(clear Negative transparent) #5 (1% sucrose Clear transparent No change(clear Negative solution) transparent) #6 (1% lactose Clear transparent No change(clear Negative solution) transparent) #7 (1% glycogen Translucent Red-brown Positive solution) #8 (1% starch Slightly translucent Blue-black Positive solution) #9 (protein solution) Translucent No change(clear Negative transparent) #10 (beer) Brown- yellow No change(clear Negative transparent) #11 (distilled water) Clear transparent No change(clear Negative transparent) #12 (unknown Slightly translucent Red-brown Positive solution 318)* 5 * Unknown 318 (7.5mL) Table 2: Observations of the Benedict's Test for Reducing Sugars Test Tube Colour before Colour after Colour change Positive/Negative adding adding Benedict's Benedict's solution solution #1 (1% glucose Clear transparent Light Blue Light red-brown Positive solution) #2 (0.3% Clear transparent Light blue No change (light Negative glucose-1- blue) phosphate) #3 (1% maltose Clear transparent Light blue Red-brown Positive solution) #4 (honey Slightly Light blue Brown Positive solution) translucent #5 (1% sucrose Clear transparent Light blue No change (light Negative solution) blue) #6 (1% lactose Clear transparent Light blue Red Positive solution) #7 (1% glycogen Translucent Light blue No change (light Negative solution) blue) #8 (1% starch Slightly Light blue No change (light Negative solution) translucent blue) #9 (protein Translucent Light blue No change(light Negative solution) blue) #10 (beer) Brown- yellow Green-blue Pale thick yellow Positive* 1 6 #11(distilled Clear transparent Light blue No change Negative water) #12 (Unknown Slightly Light blue Red-orange Positive solution 318)* translucent *1Positive because although it did not turn red/brown, there was a colour change and a coloured precipitate formed. * Unknown 318 (7.5mL) Table 3: Observations for the Biuret Test for Protein Test Tube Colour Before ColourAfter Positive/Negative #1 (1% glucose Clear transparent Slightly blue(due to Negative solution) CuSo 4 #2 (0.3% glucose-1- Clear transparent Slightly blue(due to Negative phosphate) CuSo 4 #3 (1% maltose Clear trans
More Less
Unlock Document

Only pages 1,2 and half of page 3 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit