EVOLUTION M2D2

Sickle cell anemia is a hereditary disorder that primarily affects people of African ancestry, but also other ethnic groups, including people of Mediterranean and Middle Eastern descent. Sickle cell disease is the most common inherited blood disorder in the United States with more than 70,000 Americans affected; 1 in 500 African Americans (NIH, 2007). Furthermore, 1 in 12 African Americans carry an allele for the sickle cell trait, but do not have the disease itself (NIH, 2007). Sickle cell anemia is determined by a single gene and occurs when a person inherits two abnormal alleles (one from each parent), causing a change in the hemoglobin molecule found in red blood cells. Hemoglobin is the molecule in red blood cells that carries oxygen throughout the body. People afflicted with sickle cell anemia have atypical hemoglobin that distorts that shape of red blood cells, changing them from round to crescent- (or sickle-) shaped, which is how the disease got its name. In this activity we will study the incidence of hemoglobin alleles and malaria using a simplified population genetics model. Our population genetics model will focus on a single gene for hemoglobin and its two alleles that code for normal hemoglobin and the allele that codes for the sickle cell trait. You will explore three versions of this population genetics model. The first scenario models the how the frequency of this gene might change from one generation to the next in the absence of natural selection. The last two versions model the behavior of the hemoglobin gene in response to natural selection. You will complete the exercises outlined in the attached document and submit your answers to the accompanying questions in the appropriate discussion board. Please see the attached document for an introduction to the activity. Genetics of Sickle Cell References NIH. (2007). Sickle Cell Disease. Retrieved from http://ghr(dot)nlm(dot)nih(dot)gov/condition/sickle-cell-disease. Instructions to Learners: Worksheet—Conduct the experiments described in "Genetics of Sickle Cell" and fill in the tables provided using the data collected, respond to the questions associated with each experiment (Natural Selection I - US and Natural Selection II - Africa) and submit your completed worksheet in the appropriate dropbox. Please compose a summary of your answers and post the summary to the discussion board. Summary Questions—Please develop clear and concise answers to these questions for use in the Module 3 discussion, "The Genetics of Sickle Cell Anemia Part 2" These responses will be posted to the Discussion Board and shared with the class and evaluated by the instructor. Post your response to the Summary Questions by creating a ‘comment' and submitting your response. You must also read other student's responses and respond to at least two with a clear and thoughtful follow-up explaining whether you agree or disagree, supporting your responses with evidence from your readings or other credible sources. Please include in-text citations and bibliographic information for all sources other than your textbook. PLEASE COMPLETE THE WORKSHEET AND SUMMARY QUESTION