3 Protein Synthesis and Sickle-Cell Anemia Assignment

| September 12, 2019


The goal of this assignment is for you to gain insight into how protein synthesis works and how mutations affect the physical expression of traits. Read through the information below and then follow the instructions on how to turn in this assignment.

Assignment Information-

Protein synthesis is the process by which the genetic code puts together proteins in the cell. DNA, residing in the nucleus of the cell contains the blueprint for each specific protein.

  • The four letters or “bases” in the DNA “alphabet” (adenine-A, thymine-T, cytosine-C, and guanine-G) combine in various sequences and quantities to form “words” or codons.
  • Codons are made up of three “letters” or bases (A, T, C, G) and they form amino acids. Each amino acid is made up of three letters. There are 20 different amino acids which combine in various sequences and quantities to formulate the hundreds of thousands of proteins that make up human beings.
  • The genetic code is redundant in that each amino acid can be coded for in more than one way (e.g. lysine can be coded for by TTT or TTC).

Hemoglobin is a protein made up of two chains of amino acids. A mutation occasionally occurs in one of the bases of the second amino acid chain of hemoglobin. This mutation leads of one of the bases (A, T, C, or G) results in the formation of an abnormal protein. Individuals that have this abnormal protein have a condition called sickle-cell anemia. Sickle-cell anemia results in the red blood cells becoming distorted and rigid (sickle shaped) and small clots are formed which deprive the cells of oxygen. Individuals with sickle-cell anemia are often ill and before modern medicine often didn’t live to reproduce.

The first twelve amino acids that make up the second chain in the hemoglobin molecule are listed below. The amino acids sequence below is for an individual with normal hemoglobin (each amino acid is indicated by the first three letters of its name). The mutation that causes sickle cell resides in this part of the protein.

VAL-HIS-LEU-THR-PRO-GLU-GLU-LYS-SER-ALA-VAL-THR

Your Assignment: Assume you are a researcher studying sickle-cell anemia. You have been given two unlabeled samples of DNA sequences. One is from a healthy individual, and one is from an individual with sickle-cell anemia. Using the table of amino acids (below) and the sequence of amino acids for normal hemoglobin (above), determine which strand is normal and which codes for the abnormal hemoglobin. (HINT: Remember that a codon is a series of three nucleotide bases that code for a particular amino acid).

Leucine: AAT, AAC, GAG, GAC Proline: GGA, GGG, GGT, GGC

Lyseine: TTT, TTC Serine: AGA, AGG, AGT, AGC

Valine: CAT, CAG, CAA, CAC Histidine: GTA, GTG

Alanine: CGG, CGA, CGG, CGT Glutamic Acid: CTT, CTC

Threnine: TGA, TGG, TGT, TGC

Individual A:

DNA Sequence- C A T G T A A A T T G A G G A C T T C T T T T T A G A C G G C A T T G A

Amino acids-

Individual B:

DNA Sequence- C A T G T A A A T T G A G G A C A T C T T T T T A G A C G G C A T T G A

Amino acids-

1 Who has sickle-cell anemia?

2. How did you make this determination (include a couple of sentences stating how you figured out who has sickle cell anemia)?

Turning in your assignment.

  • Anwers questions 1 and 2 above. For question two you should include several sentences explaining how you arrived at the answer that you did
  • Copy and paste your answers into the SUBMISSIONS box (not as a file attachment).

Last Step for the Assignment: Once you have completed and turned in your exercise read my notes below to make sure you completed the assignment accurately.

Protein Synthesis and Sickle Cell Anemia- Assignment Review

Individual A is normal.

This can be determined by dividing the bases into units of three (there are three bases in a codon). Then determine the amino acids that are spelled out by the bases. For instance in the DNA sequence for Individual A it has the following bases that I have separated into units of three. I then listed the amino acids that are coded for by the bases.

C A T-G T A- A A T- T G A -G G A- C T T

Val- His- Leu- Thr- Pro-Glu

Individual A’s sequence of DNA is the same as the normal sequence of amino acids in the middle of the page. Individual B’s sequence of DNA has a difference in the 6th position, it codes for Valine instead of Glutamic Acid. Thus, Individual B is the one who has sickle cell anemia because of the mutation of one of the bases in the 6th position.

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