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DNA codes genetic information so that polypeptides and, ultimately, protein molecules will be produced by cells. In this activity you will work with a hormone called somatostatin and two versions of beta hemoglobin. Somatostatin is a hormone which regulates the rate at which glucose and other nutrients are absorbed by the digestive tract. Beta hemoglobin is one of the components in the structure of hemoglobin, the pigment molecule found in red blood cells. At the conclusion of this activity you will better understand how the process of protein synthesis is carried out. You will also be able to see how an error, or mutation, in the DNA code occurs, causing abnormally shaped red blood cells.

You must work logically and carefully! Be careful because precision really counts for information coded into genetic messages!!! This activity is a group activity so you will be able to check each other's thinking!


  • broad-tipped colored markers --3 different colors
  • two strips of paper approximately 8x15 cm. wide by 80-100 cm. long (adding machine tapes)
  • translation chart (codons and amino acids)
  • prepared slides or video images of normal and sickle cell red blood cells

General procedure:

In your group you will work cooperatively to complete Part I and Part II of this activity. Your group will prepare a short delivery to present your findings to your class. You will use the visuals which you construct to facilitate your delivery. Groups will be graded on the oral presentations.

Individually you will complete in your notebook four discussion questions which will further assess your understanding of the concepts you have explored.


Part I


Below you will find the 5 to 3 strand of DNA for the gene for somatostatin, a hormone produced by the pancreas.


  1. Determine the coding strand, that is the 3 to 5 strand, for this gene. Write its base sequence on one of your strips of paper. Make your letters bold so they will be visible to the audience during your delivery. Place your sequence near the top of your strip! Label the direction of your coding strand.
    • What is the significance of the 3 to 5 strand for the process of protein synthesis?
  2. Using the coding strand base sequence, determine the RNA sequence for the somatostatin gene. Using another color pen write your RNA base sequence directly below your DNA information. You now should have two codes in two different colors on your strip of paper.
    • What step of protein synthesis did you just carry out?
    • How are the two codes shown on your paper related?
  3. Using a codon/amino acid table, determine the amino acid sequence of your transcribed gene. Write the polypeptide's composition in a new color, making certain that you line up each codon with its appropriate amino acid. Use amino acid abbreviations on your strip.
    • What step of protein synthesis did you just complete?
    • Support your answer.
  4. Discuss with your partners why and how you just completed protein synthesis. Be prepared to use these terms in your oral presentation: coding strand, transcription, translation, codon, 3 to 5, 5 to 3, DNA, somatostatin, hormone, polypeptide, messenger RNA.

Divide up your presentation tasks so your delivery will flow smoothly when your group presents.

Part II

  1. Observe preserved microscope slides or video images of human blood which show normal red blood cells and sickle-shaped red blood cells. 4. Describe the differences you observe between the two types of red blood cells. 5 Sickle cells are characteristic of the condition known as sickle cell anemia. What physiological function would be affected by the sickle cell's shape?
  2. Normal hemoglobin is called hemoglobin A, while the hemoglobin that creates sickle cells is called hemoglobin S.
    • Since hemoglobin is made of polypeptides, how might two forms of this protein be possible?
    • Observe below two amino acid sequences for the first eight amino acids for beta hemoglobin. The first sequence is for normal hemoglobin: the other is a mutant form. What is mutation?

      val-his-leu-thr-pro-glu-glu-lys (normal)

      val-his-leu-thr-pro-val-glu-lys (mutated)

    • Locate difference(s) between the two forms of the polypeptide? On this sheet circle the differences(s). Describe the difference(s). 9 Using a codon chart, figure out why this mutation might have occurred.
    • Discuss your response in terms of codons and DNA triplets.
    • Why do we refer to this deviation in the code as a point mutation?
  3. Prepare a visual that illustrates the location of the mutation and how it come to affect the polypeptides's structure. Use your second strip of paper and your colored markers to make a clear and concise visual.
  4. Prepare an oral presentation that effectively describes the mutation that effectively describes the mutation for sickle cell trait.

Discussion Questions: Please complete these questions as individual work. Use your notebook.

  1. Discuss how Part I of this activity walks you through the process of protein synthesis.
  2. Discuss how a point mutation causes sickle cell anemia.
  3. Discuss why genetic codes have to be precise.
  4. Is it possible for a point mutation to have no consequence on the amino acid sequence of the polypeptide produced? Support your response with some examples.

Susan Johnson Goldie
East Longmeadow High School
180 Maple Street
East Longmeadow, MA 01028

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