Four Major Biological Macromolecules
Introduction The objective of this experiment is to identify if the 12 provided solutions contain starch, glycogen, reducing sugars or proteins. The four major biological macromolecules are carbohydrates, lipids, proteins and nucleic acids. Abundant elements in the world such as carbon and nitrogen bond in different ways to form many different molecules. The functional groups are what determine their characteristics. During the experiment, there will be 3 test. The iodine test is completed to test for starch and glycogen. When iodine is mixed with a solution that contains starch, the amylose will react, turning the solution blue/black. If iodine is mixed with a solution containing glycogen, it will
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turn reddish/brown due to the multibranched nature of glycogen. Forms of carbohydrates are mono and polysaccharides. Both glycogen and starch are a form of a polysaccharide structure, but differ in their shape and branching. Glycogen is highly branched while starch contains amylose (unbranched) and amylopectin ( branched). Furthermore, the Benedicts test is done to discover reducing sugars in solutions. Simple straight chained sugars contain an aldehyde group which reacts with the Cu+ ions from the benedicts solution. For the benedict test to work, the mixed solution must be heated. If the solution contains a precipitate ranging from many colors, that solution contains reducing sugars. The last test done is the biuret test to discover the presence of proteins. Proteins are built in the form of long polymer chains that consist of amino acids. There are 7 essential amino acids which come from only the foods that are consumed. 13 amino acids are already available inside the human body. The biuret test will result in the solution turning violet if Cu++ ions react with peptide bonds. Peptide bonds are bonds that link amino acids to create protein. During the experiment, there will be positive and negative controls. A positive control will conclude in a positive result if procedures are followed. A negative control results in a negative result if the expermint ws properly done.
Materials and Method
6384
2013
Pages 14-18
( Biology Department, 2013 )
Results
Table 1: Qualitative Observation During Iodine Test For Starch and Glycogen
Solution ( 15 ml ) Solutions Color Iodine added
1) 1% glucose clear Yellow
2) 0.3% glucose-1-phosphate clear Yellow
3) 1% maltose clear Yellow
4) Honey solution clear Yellow
5) 1% sucrose clear Yellow
6) 1% lactose clear Yellow
7) 1% glycogen clear Red/brown
8) 1% starch clear Blue
9) Protein clear Yellow
10) beer clear Yellow
11) Distilled water clear Yellow
12) Unknown clear Yellow
Link: If starch is present, the solution will turn blue, while glycogen will turn red/brown in the presence of iodine.
Table 2: Qualitative Observation During Benedict 's Test For Reducing Sugars
Solution ( 15 ml ) Org. Solution with Benedict 's solution Boiled (5 min.)
1)1% glucose Blue solution red/brown
2)0.3% glucose-1-phosphate Blue solution blue
3)1% maltose Blue solution red/brown
4)Honey solution Blue solution brown
5)1% sucrose Blue solution blue
6)1% lactose Blue solution red/brown
7)1% glycogen Blue solution blue
8)1% starch Blue solution blue
9)Protein Blue solution blue
10)Beer Turquoise orange
11)Distilled water Blue solution blue
12)Unknown Blue solution blue
Link: The Benedict solution contains cupric ions which react with an aldehyde group in a straight chained sugar.
Table 3:Qualitative Observation During Biuret Test For Protein
Solution ( 15 ml ) Solution with 2 ml NaOH 5 Drops 1% CuSO4
1)1% glucose clear blue
2)0.3% glucose-1-phosphate clear blue
3)1% maltose clear blue
4)Honey solution clear blue
5)1% sucrose clear blue
6)1% lactose clear blue
7)1% glycogen clear blue
8)1% starch clear blue
9)Protein clear purple
10)beer yellow black/purple
11)Distilled water clear blue
12)Unknown clear blue
Link: A positive test will result in the solution turning violet
Discussion
During the lab, there were a few sources of error.
Firstly, a source of error may occur during the Benedict 's test. Positive results may occur when their should not be. This is due to the fact that there may be a presence of another substance that can be oxidized other than reducing sugars. Furthermore, another source of error may be the dirty test tubes which may sway some reactions when solutions are mixed. Measurements may be another source of error. Such as using a plastic measuring cup can measure off by +/- 5%, and estimating the amount of solution in half a pipette. To improve this lab, and the Benedict test, another test should be done for non-reducing sugars that may give positive results. Another way to improve the lab is to use distilled water as a solution for comparision. The distilled water will not result in a positive control in the test due to the fact that water does not contain any macromolecules. The water can be compared with other solutions for a negative control. The results for iodine test indicate that solutions 1,2,3,4,5,6,9,10 and 11 turn yellow when mixed with iodine and therefore the solutions do not contain starch or glycogen. The yellow is a result from a colorless solution mixed with iodine. Solutions 7 and 12 turned red/brown when iodine was added. Conclusions can be made that these solutions contain glycogen. The highly branched structure reacting with iodine and gives it that red/brown color. Furthermore, solution 8 turned blue/purple which is an indication that it is starch, and it was also expected to result positive because it was 1% starch solution. Solution 7 therefore contains amylose and amyloepectin. But it is the amylose that initially reacts with iodine creating a blue color. Secondly, the results for the Benedicts test showed that solutions 2, 5, 7, 8, 9, 11 and 12 had a negative control. No color change. Therefore these solutions do not contain any molecules that can reduce cupic ions such as a reducing sugar. An
example may be distilled water, which contains no reducing sugars because it is composed of 2 hydrogen and 1 oxygen atom. The solutions such as water, glucose-1-phosphate or starch do not contain an aldehyde group. On the other hand, solutions 1, 3, 4, 6 and 10 changed to a red/brown and orange color when heated with the Benedict solution. The red/brown color indicates that there is an abundant amount of reducing sugar present. Sugars that contain an aldehyde group reduce cupric ions. The product of the reduced ion will form a precipitate. Overall these solutions contain easily oxidized compounds such as a reducing sugar ( aldehyde group ). Lastly, the biuret test results show that solutions 9 and 10 contain proteins. These proteins are formed by chains of amino acids which are held together by peptide bonds. Peptide bonds within proteins react with Cu++, resulting in a purple solution. Protein (9) and beer (10) were expected to result in a positive control because the protein contains peptide bonds. Beer also contains protein, but only a small trace. The other solutions did not turn purple, therefore do not contain proteins and resulted in a negative control. After completing the experiment, the results indicate that the unknown solution contains glycogen. This is due to the fact that the iodine test indicates that when the unknown solution reacted with iodine, the solution changed to a red/brown color. This is a characteristic that occurs when iodine is mixed with glycogen. The red/brown color is due to the very branched structure of glycogen. The other test result in a negative control since the "unknown" is not a protein or reducing sugar. Overall, 1% glycogen and starch solution were expected to contain either glycogen and starch, and infact did have a positive control during the iodine test. The unknown solution was also discovered when the solution had a positive control when turning red/brown which results in unknown solution being a glycogen. In the benedicts test, solutions 2,5,7,8,9,11 and 12 have negative control, while solutions 1,3,4,6,and 10 change colors when heated resulting in a positive control. Lastly, solutions 9 and 10 were identified as having traces of protein since a positive control occurred during the biuret test. In the end solutions expected to have a positive control in each individual test did obtain one.
References
Agashe, V. (1975, October 25). Benedict 's Test For Sugar in Urine. Journal of Clinical Pathology. Retrieved September 21, 2013, from www.ncbi.nlm.nih.gov/pmc/articles/PMC477542/
Johnson, B. (n.d.). Elsevier. Elsevier. Retrieved September 21, 2013, from http://www.journalofdairyscience.org/article/S0022-0302(52)93762-4/abstract
[The nature of glycogen complexing with iodine in... [Biokhimiia. 1986] - PubMed - NCBI. (n.d.). National Center for Biotechnology Information. Retrieved September 21, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/2423143
APA formatting by BibMe.org.
turn reddish/brown due to the multibranched nature of glycogen. Forms of carbohydrates are mono and polysaccharides. Both glycogen and starch are a form of a polysaccharide structure, but differ in their shape and branching. Glycogen is highly branched while starch contains amylose (unbranched) and amylopectin ( branched). Furthermore, the Benedicts test is done to discover reducing sugars in solutions. Simple straight chained sugars contain an aldehyde group which reacts with the Cu+ ions from the benedicts solution. For the benedict test to work, the mixed solution must be heated. If the solution contains a precipitate ranging from many colors, that solution contains reducing sugars. The last test done is the biuret test to discover the presence of proteins. Proteins are built in the form of long polymer chains that consist of amino acids. There are 7 essential amino acids which come from only the foods that are consumed. 13 amino acids are already available inside the human body. The biuret test will result in the solution turning violet if Cu++ ions react with peptide bonds. Peptide bonds are bonds that link amino acids to create protein. During the experiment, there will be positive and negative controls. A positive control will conclude in a positive result if procedures are followed. A negative control results in a negative result if the expermint ws properly done.
Materials and Method
6384
2013
Pages 14-18
( Biology Department, 2013 )
Results
Table 1: Qualitative Observation During Iodine Test For Starch and Glycogen
Solution ( 15 ml ) Solutions Color Iodine added
1) 1% glucose clear Yellow
2) 0.3% glucose-1-phosphate clear Yellow
3) 1% maltose clear Yellow
4) Honey solution clear Yellow
5) 1% sucrose clear Yellow
6) 1% lactose clear Yellow
7) 1% glycogen clear Red/brown
8) 1% starch clear Blue
9) Protein clear Yellow
10) beer clear Yellow
11) Distilled water clear Yellow
12) Unknown clear Yellow
Link: If starch is present, the solution will turn blue, while glycogen will turn red/brown in the presence of iodine.
Table 2: Qualitative Observation During Benedict 's Test For Reducing Sugars
Solution ( 15 ml ) Org. Solution with Benedict 's solution Boiled (5 min.)
1)1% glucose Blue solution red/brown
2)0.3% glucose-1-phosphate Blue solution blue
3)1% maltose Blue solution red/brown
4)Honey solution Blue solution brown
5)1% sucrose Blue solution blue
6)1% lactose Blue solution red/brown
7)1% glycogen Blue solution blue
8)1% starch Blue solution blue
9)Protein Blue solution blue
10)Beer Turquoise orange
11)Distilled water Blue solution blue
12)Unknown Blue solution blue
Link: The Benedict solution contains cupric ions which react with an aldehyde group in a straight chained sugar.
Table 3:Qualitative Observation During Biuret Test For Protein
Solution ( 15 ml ) Solution with 2 ml NaOH 5 Drops 1% CuSO4
1)1% glucose clear blue
2)0.3% glucose-1-phosphate clear blue
3)1% maltose clear blue
4)Honey solution clear blue
5)1% sucrose clear blue
6)1% lactose clear blue
7)1% glycogen clear blue
8)1% starch clear blue
9)Protein clear purple
10)beer yellow black/purple
11)Distilled water clear blue
12)Unknown clear blue
Link: A positive test will result in the solution turning violet
Discussion
During the lab, there were a few sources of error.
Firstly, a source of error may occur during the Benedict 's test. Positive results may occur when their should not be. This is due to the fact that there may be a presence of another substance that can be oxidized other than reducing sugars. Furthermore, another source of error may be the dirty test tubes which may sway some reactions when solutions are mixed. Measurements may be another source of error. Such as using a plastic measuring cup can measure off by +/- 5%, and estimating the amount of solution in half a pipette. To improve this lab, and the Benedict test, another test should be done for non-reducing sugars that may give positive results. Another way to improve the lab is to use distilled water as a solution for comparision. The distilled water will not result in a positive control in the test due to the fact that water does not contain any macromolecules. The water can be compared with other solutions for a negative control. The results for iodine test indicate that solutions 1,2,3,4,5,6,9,10 and 11 turn yellow when mixed with iodine and therefore the solutions do not contain starch or glycogen. The yellow is a result from a colorless solution mixed with iodine. Solutions 7 and 12 turned red/brown when iodine was added. Conclusions can be made that these solutions contain glycogen. The highly branched structure reacting with iodine and gives it that red/brown color. Furthermore, solution 8 turned blue/purple which is an indication that it is starch, and it was also expected to result positive because it was 1% starch solution. Solution 7 therefore contains amylose and amyloepectin. But it is the amylose that initially reacts with iodine creating a blue color. Secondly, the results for the Benedicts test showed that solutions 2, 5, 7, 8, 9, 11 and 12 had a negative control. No color change. Therefore these solutions do not contain any molecules that can reduce cupic ions such as a reducing sugar. An
example may be distilled water, which contains no reducing sugars because it is composed of 2 hydrogen and 1 oxygen atom. The solutions such as water, glucose-1-phosphate or starch do not contain an aldehyde group. On the other hand, solutions 1, 3, 4, 6 and 10 changed to a red/brown and orange color when heated with the Benedict solution. The red/brown color indicates that there is an abundant amount of reducing sugar present. Sugars that contain an aldehyde group reduce cupric ions. The product of the reduced ion will form a precipitate. Overall these solutions contain easily oxidized compounds such as a reducing sugar ( aldehyde group ). Lastly, the biuret test results show that solutions 9 and 10 contain proteins. These proteins are formed by chains of amino acids which are held together by peptide bonds. Peptide bonds within proteins react with Cu++, resulting in a purple solution. Protein (9) and beer (10) were expected to result in a positive control because the protein contains peptide bonds. Beer also contains protein, but only a small trace. The other solutions did not turn purple, therefore do not contain proteins and resulted in a negative control. After completing the experiment, the results indicate that the unknown solution contains glycogen. This is due to the fact that the iodine test indicates that when the unknown solution reacted with iodine, the solution changed to a red/brown color. This is a characteristic that occurs when iodine is mixed with glycogen. The red/brown color is due to the very branched structure of glycogen. The other test result in a negative control since the "unknown" is not a protein or reducing sugar. Overall, 1% glycogen and starch solution were expected to contain either glycogen and starch, and infact did have a positive control during the iodine test. The unknown solution was also discovered when the solution had a positive control when turning red/brown which results in unknown solution being a glycogen. In the benedicts test, solutions 2,5,7,8,9,11 and 12 have negative control, while solutions 1,3,4,6,and 10 change colors when heated resulting in a positive control. Lastly, solutions 9 and 10 were identified as having traces of protein since a positive control occurred during the biuret test. In the end solutions expected to have a positive control in each individual test did obtain one.
References
Agashe, V. (1975, October 25). Benedict 's Test For Sugar in Urine. Journal of Clinical Pathology. Retrieved September 21, 2013, from www.ncbi.nlm.nih.gov/pmc/articles/PMC477542/
Johnson, B. (n.d.). Elsevier. Elsevier. Retrieved September 21, 2013, from http://www.journalofdairyscience.org/article/S0022-0302(52)93762-4/abstract
[The nature of glycogen complexing with iodine in... [Biokhimiia. 1986] - PubMed - NCBI. (n.d.). National Center for Biotechnology Information. Retrieved September 21, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/2423143
APA formatting by BibMe.org.