Experiment 1: Testing for Proteins
Data Tables
Table 1: Testing for Proteins Results
Sample
Initial Color
Final Color
Is Protein Present?
1. Albumin Solution
2. Gelatin Solution
3. Glucose
4. Water
5. Unknown
Post-Lab Questions
Record your hypothesis about what will happen when Biuret solution is mixed with the solutions from test tubes 1, 2, 3, and 4 here. Be sure to use scientific reasoning to support your hypothesis.
Write a statement to explain the molecular composition of the unknown solution based on the results obtained during testing with the Biuret solution and each sample solution.
Diet and nutrition are closely linked to the study of biomolecules. How should you monitor your food intake to ensure the cells in your body have the materials necessary to function?
There are other types of reagents used to determine what type of biomolecule a substance is. For example, copper ions present in Benedictâs reagent reacts with the free end of any reducing sugars, such as glucose, when heated. Originally blue in color, these copper ions are reduced by the sugar, and produce an orange-red colored precipitate. Alternatively, iodine-potassium iodide (IKI) may also be used when working with starch. IKI contains special tri-iodine ions which interact with the coiled structure of a starch polymer. Prior to a reaction, the IKI displays a yellow-brown color; however, after reacting with starch, a dark purple or black color is presented.
The molecule pictured below produced a blue color when tested with Benedictâs reagent, a yellow color when tested with IKI, and a violet color when tested with Biuret reagent. Based on the structure shown below and these chemical results, what kind of biomolecule is this?
Experiment 1: Testing for Proteins
Data Tables
Table 1: Testing for Proteins Results
| Sample | Initial Color | Final Color | Is Protein Present? |
|---|---|---|---|
| 1. Albumin Solution | |||
| 2. Gelatin Solution | |||
| 3. Glucose | |||
| 4. Water | |||
| 5. Unknown |
Post-Lab Questions
Record your hypothesis about what will happen when Biuret solution is mixed with the solutions from test tubes 1, 2, 3, and 4 here. Be sure to use scientific reasoning to support your hypothesis.
Write a statement to explain the molecular composition of the unknown solution based on the results obtained during testing with the Biuret solution and each sample solution.
Diet and nutrition are closely linked to the study of biomolecules. How should you monitor your food intake to ensure the cells in your body have the materials necessary to function?
There are other types of reagents used to determine what type of biomolecule a substance is. For example, copper ions present in Benedictâs reagent reacts with the free end of any reducing sugars, such as glucose, when heated. Originally blue in color, these copper ions are reduced by the sugar, and produce an orange-red colored precipitate. Alternatively, iodine-potassium iodide (IKI) may also be used when working with starch. IKI contains special tri-iodine ions which interact with the coiled structure of a starch polymer. Prior to a reaction, the IKI displays a yellow-brown color; however, after reacting with starch, a dark purple or black color is presented.
The molecule pictured below produced a blue color when tested with Benedictâs reagent, a yellow color when tested with IKI, and a violet color when tested with Biuret reagent. Based on the structure shown below and these chemical results, what kind of biomolecule is this?
Related textbook solutions
Related questions
Table 1: Testing for Proteins Results | |||
Sample | Initial Color | Final Color | Protein Present |
1 - Albumin Solution | |||
2 - Gelatin Solution | |||
3 - Glucose | |||
4 - Water | |||
5 - Unknown | |||
Post-Lab Questions
- Record your hypothesis about what will happen when Biuretsolution is mixed with the solutions from test tubes 1, 2, 3, and 4here. Be sure to use scientific reasoning to support yourhypothesis.
- Write a statement to explain the molecular composition of theunknown solution based on the results obtained during testing withthe Biuret solution and each sample solution.
- Diet and nutrition are closely linked to the study ofbiomolecules. How should you monitor your food intake to insure thecells in your body have the materials necessary to function?
- There are other types of reagents used to determine what typeof biomolecule a substance is. For example, copper ions present inBenedictâs reagent reacts with the free end of any reducing sugars,such as glucose, when heated. Originally blue in color, thesecopper ions are reduced by the sugar, and produce an orange-redcolored precipitate. Alternatively, iodine-potassium iodide (IKI)may also be used when working with starch. IKI contains specialtri-iodine ions which interact with the coiled structure of astarch polymer. Prior to a reaction, the IKI displays ayellow-brown color; however, after reacting with starch, a darkpurple or black color is presented.
The molecule pictured below produced ablue color when tested with Benedictâs reagent, a yellow color whentested with IKI, and a violet color when tested with Biuretreagent. Based on the structure shown below and these chemicalresults, what kind of biomolecule is this?
Data Table 1. Sugar Tests with BenedictâsReagent.
Test tube | Substance | Hypothesis | Final color | Test results for |
1 | Distilled water | |||
2 | Glucose solution | |||
3 | Starch solution | |||
4 | Table sugar | |||
5 | Splenda® | |||
6 | Sweet'N Low® | |||
7 | Milk | |||
8 | Juice | |||
9 | Potato |
Questions
1. Did the table sugar solution test positive or negative forreducing sugars? Explain why you received these
2. Do Splenda® and SweetâN Low® test positive or negative forreducing sugars? List the ingredients found in each of theseproducts. Underline the ingredient that is the artificialsweetener. (Hint: There is only one artificial sweetener in each ofthe products. Refer to the Introduction.)
3. What is the relationship of glucose and dextrose? How doesthis relationship influence the test results for Splenda® andSweetâN Low®?
4. A common artificial sweetener found in Equal®, NutraSweet®,and many diet sodas is aspartame(C14H18N2O5). Would asample of pure aspartame test positive or negative for reducingsugars? (The pure sample does not contain other ingredients, suchas dextrose, maltodextrin, or calcium silicate.)
5. Unlike other sweeteners, Splenda® may be used in cookingbecause it does not break down at higher temperatures. Many recipescall for Splenda® instead of table sugar. Is a cake baked withSplenda® actually sugar-free? How might this affect a personconcerned with blood sugar levels?
Exercise 2: Detection of Starch
Data Table 2. Starch Tests with IKIIndicator.
Test tube | Substance | Hypothesis | Final color | Test results for starch |
1 | Distilled water | |||
2 | Glucose solution | |||
3 | Starch solution | |||
4 | Table sugar | |||
5 | Splenda® | |||
6 | SweetâN Low® | |||
7 | Milk | |||
8 | Juice | |||
9 | Potato |
Questions
1.Which sugar substitute tested positive for presence of starch?This sugar substitute contains a starch derived from corn orpotatoes. List the ingredient that is the starch.
2. List three examples of polysaccharides in living organisms.Describe the structural orientations of each.
3. When a human consumes starch, the polysaccharides are brokendown into simple sugars, which are converted to polysaccharides forstorage in the cells. However, simple sugars are used by the cellto perform work. Describe why it is necessary to change the form ofthe carbohydrate in the body.
Exercise 3: Converting Starch to Sugar
Data Table 3. Conversion of Starch to the SugarMaltose.
Test tube | Substance + | Final color | Test results for | Test results for |
1 | Distilled water | ---------- | ||
2 | Distilled water | ---------- | ||
3 | Starch solution | ---------- | ||
4 | Starch solution | ---------- |
Questions
1. What type of reaction is the conversion of starch to maltose?Describe what occurs during the reaction.
2. Is maltose a reducing sugar or a non-reducing sugar? Supportyour answer with information in Data Table 3. Maltose is a reducingsugar. Explain why by finding a supporting reference.
