Danielle is insisting that both families have blood type tests to ensure that they have the right babies.

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Virgil Waters
6 years ago
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Danielle and Michael had twins, a boy, Michael, Jr., and a girl, Michelle. Danielle is convinced that there was a mix-up and she was given the wrong baby girl. Tonja and Michael Jr.

1 Lab: The Genetics of Blood Type Period: Adapted from Were the babies switched? 2016 Drs. Jennifer Doherty and Ingrid Waldron, U. of Penn. Biology Department Name: Date: Problem: Were the babies switched? Two couples had babies on the same day in the same hospital. Denise and Earnest had a girl, Tonja. Danielle and Michael had twins, a boy, Michael, Jr., and a girl, Michelle. Danielle is convinced that there was a mix-up and she was given the wrong baby girl. Tonja and Michael Jr. look much more like twins since they both had darker skin, while Michelle had lighter skin. Danielle is insisting that both families have blood type tests to ensure that they have the right babies. Background: Blood Types and Genetics Each person has one of the 4 possible blood types shown in this chart. The difference between the different types of blood is the type of molecule present on the surface of the red blood cells in that blood. A Person With: Has: Type A blood Type A molecules on the surface Type B blood Type B molecules on the surface Type AB blood Type A and B molecules on the surface Type O blood Neither A nor B molecules on the surface Blood type is controlled by a single gene that is located on chromosome #9. There are 3 possible alleles for that gene. We use capital letters to represent each of these alleles because they are co-dominant to each other. Allele A B O Allele A tells the body to put type A molecules on the surface of red blood cells. Allele B tells the body to put type B molecules on the surface of red blood cells. Allele O is inactive. It doesn t tell the body to put any molecules on the surface of red blood cells. 1

2 Each person has two alleles for this gene, one inherited from his/her mother and the other inherited from his/her father. This means there are six possible combinations of alleles for this gene (genotypes). 1. Complete the following table to relate the genotypes to the different blood types (phenotypes). Some boxes have been completed for you. Genotype (The Two Alleles a Person Carries) OO Diagram (Draw what the red blood cell would look like for this genotype.) Phenotype (What Blood Type the Person Has) AO (Same as OA) Type A AA 2. Which of the genotypes listed above would provide the strongest evidence that the alleles for blood type are co-dominant? Please explain your thinking: 3. The gene for blood type is located on chromosome #9. Please mark the location of each allele for blood type on the karyotype for each person described below. A person who has the genotype BO for blood type: A person who has type AB blood: 2

3 4. If we know the blood types of two parents, we can use Punnett squares to predict the expected blood types of their children. For example, if a mother had the AA genotype and father had AB genotype, what genotypes would you expect in their children? (Please support your answer with a Punnett square.) 5. Is it possible for a child to have a blood type that is different than either of its parents? (Please support your answer with one or more Punnett squares.) Procedure: Using Immune Responses to Test Blood Types The type A and type B molecules on the surface of red blood cells are called antigens because they can stimulate the body to produce an immune response. Part of the body s immune response is to produce antibodies, which are molecules that bind to antigens to help white blood cells find and destroy them. Each specific type of antibody binds to a specific antigen. For example, anti-b antibodies in the blood bind to type B antigens, but not to type A antigens. Examine the diagram to the right, showing antibodies binding to the antigens on the red blood cells. What do you notice? What effect do you think this would have on the person s blood? When antibodies bind to the antigens on red blood cells, they cause the blood cells to clump together and clot. In the body, this can block blood vessels and cause serious problems including death. Fortunately, your body generally does not make antibodies against any antigens that are a normal part of your body. 6. Use the diagrams to fill in the blanks below. For type A blood, you have: For type B blood, you have: For type AB blood, you have: For type O blood, you have: 3

4 7. Explain how a blood transfusion of type B blood could be fatal for a person with type A blood. Be specific. 8. When you mix blood with its matching antibody, the clumping and clotting of the blood is visible to the naked eye. If you had a supply of both anti-a and anti-b antibodies, how might you use this as a test to identify the type of an unidentified sample of blood? (Hint: Be sure you think of a way to distinguish ALL 4 possible blood types.) A. Describe your procedure (generally): B. What evidence will allow you to identify each blood type? I can conclude that it is blood type A If I observe B AB O Please stop and raise your hand. Your teacher will check your procedure and show you a demonstration of what this clumping and clotting looks like. 4

5 Data & Observations: Decide how you will use this procedure to solve the problem at the beginning of this lab. Please record your data and observations on this page. Be sure that you record your results in a way that is organized and specific enough for another person to recreate your investigation! (Hint: Create a table.) 5

6 Analysis: 9. Based on your results, draw Punnett squares that show the possible genotypes for Danielle and Michael and their children. Write in the blood type for each genotype to show the possible blood types for Danielle and Michael s children. 10. Based on your results, draw Punnett squares that show the possible genotypes for Denise and Earnest and their children. Write in the blood type for each genotype to show the possible blood types for Denise and Earnest s children. 11. Who are the parents of each baby girl? How do you know? Conclusion: Please use the rubric below to help you write a formal lab conclusion for this investigation. Please type and print your conclusion & staple it to the front of this lab packet. 4 = Advanced Achieved a 3 AND discussed level of confidence in results AND identified logical next steps/next investigations. (Hint: In thinking about your level of confidence in these results, please address Danielle s initial concern about the differences in skin color in the babies. Also, in determining the identity of the parents of each girl, we have fully answered the question in this investigation, so there would not necessarily be next steps. Instead, think about the limitations of this type of testing. Is it possible that this test would have come back inconclusive?) 3 = Proficient Achieves a 2 AND connects conclusion to background knowledge. 2 = Partially Proficient Uses all relevant observations/data to support the conclusion. 1 = Basic States correct conclusion/answer to the question being investigated. Evidence & Conclusions 6

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Were the babies switched? The Genetics of Blood Typesi

Were the babies switched? The Genetics of Blood Typesi Two couples had babies on the same day in the same hospital. Denise and Earnest had a girl, Tonja. Danielle and Michael had twins, a boy, Michael,