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Lab Report on the identification of biological molecules...

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Biology Lab Report Worksheet Name: Muchai Matheri

Date: 26 September 2018

Lab Report Title: Identification of Biological Molecules Purpose: (terms defined, question to be answered): This lab exercise involves specific test methods to identify the known biomolecules. The four known biomolecules will be tested against a water control group with a reagent to determine the negative and positive results through their indication of their colors. The negative results will have the water control and the positive have the known substances

Hypothesis/ Prediction: (expected results, what you think will happen): If the solution contains a presence of a known substance then the color of the solution will test positive.

Materials: (This should be a bullet list)  16 test tubes

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Test tube holder

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Wax pencil

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450ml beaker

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Disposable pipets

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Hot plate

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Iodine reagent

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Benedicts reagent

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Sudan IV reagent

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Biuret reagent

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Starch- soluble liquid starch

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Sugar-1% glucose solution

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Lipid-corn oil

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Protein-Albumin

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Deionized water

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2 Unknown solutions

Test Method Describe the setup of experiment  Test for Starch - add 3 drops of iodine reagent to test tube A1 & A2 and gently shake the tubes to mix it. A dark blue/black color change indicates the presence of starch in A1 while A2 has a lightyellow color which has no starch present.  Test for Reducing Sugars -add 5 drops of Benedicts reagent to test tube B1&B2 and gently shake the tubes to mix. Heat the tube in boiling water for 3-5 minutes. A yellow or orange color indicates presence of reducing sugars in B1 while B2 has a light blue color in which there is no presence of reducing sugars.  Test for lipids – add 5 drops of Sudan IV reagent to test tube C1 & C2 and gently shake to mix. Let the mixture stand for 3-5 minutes. Orange globules float in the solution is not the accurate result and pink is the color which indicates lipids in C1 but also C2 has an orange color as well, so it has presence of lipids.

 Test for proteins – add 5 drops of Biuret reagent to test tube D1 & D2 and gently shake to mix. A violet/lavender color indicates the presence of proteins in D1 while D2 has no color change with the same clear appearance.

Drawing of setup…

Procedure / Steps: 1. 2.

Prepare hot water bath by placing a 450ml beaker filled half full of water on a hotplate. Label 8 clean dry tubes with wax pencil;  A1 Starch, A2 Starch control  B1 Sugar, B2 Sugar control  C1 Lipid, C2 Lipid control  D1 Protein, D2 Protein control

3. 4. 5. 6.

Use a disposable pipet to place the known substances in the respective tubes (A1-D1). Place a full pipet of Deionized water in the control test tubes (A2-D2). Observe and record the appearance of each known substance. Follow the specific test method to the known substances against the control.

7.

Observe the positive and negative results and record results in the known organic compounds.

Observations: Raw data and results (Data tables, graphs, drawings) All the solutions of the 8 test tubes appear clear before the reagents were added. The (A1-D1) tubes tested positive results of the four substances. The test tubes with deionized water (A2-D2) tested negative results.

Tables, graphs, drawings:

Known organic compound Starch Reducing sugar Lipids Proteins

Appearance of solution before testing Clear Clear Clear Clear

Test conducted

Observed (+) positive result

Observed (-) negative result

Iodine Benedict Sudan IV Albumin

Dark purple Orange Pink globules Lavender

Yellow Light blue Pink Light blue

Conclusion(s): The hypothesis is supported because this experiment demonstrates when the known substance is mixed with its respective reagent. Testing for unknown solutions is determined by adding each reagent in respective tubes of the unknown solution to determine the biomolecules that are present in them.

Errors(s): When testing for unknown solutions there were two test tubes that was accidentally mixed the wrong reagent.

Suggestion(s) for improvement: Arrange the test tubes on the test tube rack next to the similar labeled tubes accordingly....