geneticshandout - 1 Explain how the terms heterozygous and...

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Unformatted text preview: 1. Explain how the terms heterozygous and homozygous are related to homologous chromosomes. (4 points) 2a. Although there are many types of genetic disorders, each involves changes to the cells DNA. Describe how each of the following types of genetic disorders impacts the cells DNA or chromosomes. Include in your answer which of these types of disorders involves nuclear DNA and which impacts DNA found in the mitochondria. (6 points) single gene disorder chromosomal disorder mt DNA disorder. 2b. Give a specific example of a single-gene disorder and of a chromosomal disorder. Give a short description of each of the disorders selected. Your examples may not be one of the disorders discussed in lecture. (4 points) 2c. Which of these three disorders listed in 2a can be detected by examining a karyotype? Briefly support your answer. (2 points) 3a. Describe three ways "X"-linked traits and autosomal traits differ from each other. (6 points) 3b. Explain why X-linked recessive disorders are more common in males than in females. (2 points) 3c. Describe a genetic disorder not covered in lecture that is X-linked. Reference where you found this information. (4 points) Part II. Human Genetics Problems (79 points) A-C: AUTOSOMAL DISORDERS A. Autosomal Recessive Disorder: Cystic Fibrosis A1. Discuss in a fair amount of detail the biological cause of cystic fibrosis. A complete answer will include information on how the DNA is mutated, the protein that is made incorrectly in CF patients, the consequences of this defect in the protein, and the role of the ER/Golgi. (5 points) A2. Explain why carriers of CF, although they have an allele for the defective protein, are healthy and symptom free. Your answer should clearly address the relationship between the individual's DNA and the membrane proteins they make. (2 points) A3. One of my former students has a beautiful daughter with CF, Sara Elizabeth. Both the student and the child's father are healthy. Explain how these two healthy parents could have a child with CF. Include in your answer the genotype of each parent and of the child. (4 points) Please the following letter code: H - healthy h = cystic fibrosis A4. If the couple in A3 were to have a second child, what is the risk that their second child would have CF? Support your answer. Is the sex of the baby related to the risk of CF? Why or why not? (3 points) A5. With new treatments individuals affected with CF are living longer. Thus, marriage and family are a possibility. Imagine Sara Elizabeth is grown-up and preparing to marry a healthy man. What would you tell them/her about their risk for having children with CF? Please be sure to consider all possibilities. For full credit, support your answer(s) with the genotypes of all involved. (You may want to consider the best-case and worst-case scenario.) (4 points) B. Autosomal Dominant Disorder: Marfan Syndrome see exam website for more information on Marfans and Flo Hyman. B1. Flo Hyman died unexpectedly while playing volleyball. The autopsy showed she had Marfans syndrome. Given the genetic aspect of Marafan's, Flo's family was screened. (The following concerning Flos' family is not true, but made-up for this question.) Her father and sister were diagnosed with Marfans while her mother and a brother were given a clean bill of health. Create a pedigree (family tree) for Flo Hyman's family -- to include: Flo, her parents, and her two siblings. Shade in the circles/boxes of individuals with Marfan syndrome. In addition, give as much information as possible about the genotype for each member of the family. Use the following letter key: M = Marfan syndrome, m = healthy. (6 points) B2. Discuss the genetic basis for Marfan Syndrome. Include in your answer information on the gene associated with Marfan syndrome and the protein affected. Some detail is needed for full credit. (4 points) B3 Occasionally two healthy parents with no family history of Marfan Syndrome have a child who is diagnosed with the condition. Explain why it would be unusual/unexpected for two healthy parents to have a child with a dominant disorder such as Marfans. (Make sure answer the question as asked!) (2 points) C. Co-Dominance - Blood Type C1. Explain how a person could have type O blood if neither of their parents has type O blood. Give an example of parental genotypes that support your answer. (4 points) C2. Explain why an individual with type O blood is a universal blood donor, but can receive blood only type O blood. Fully support your answer. (4 points) C3. What component(s) of the plasma membrane plays a role in determining an individual's blood type? Be specific and briefly support your answer. Base some aspect of your answer on the information presented in Chapter 5. (3 points) C4. Although blood types can never be used to prove someone is the father of a particular child, they can demonstrate that someone could not be the father. In 1940 there was a famous paternity case involving Charlie Chaplin. A woman named Charlie as the father of her baby. Charlie denied the accusation and the case went to court. At the time Charlie Chaplin was judged to be the baby's father. At that time many states did not allow blood test results as evidence in cases of disputed paternity. You may/must use the blood types of the individuals to guide your answer. The baby's blood type was B, the mother's A, and Charlie Chaplin's O. (10 points) a) Based on the information in this question, give the possible genotype(s) of the woman, Charlie, the baby, and the baby's father if it's not Charlie. In some cases only one genotype is possible and in others multiple genotypes are possible. Be sure to fully think through the possible genotypes! b) Based on these genotypes, could Charlie be the babys father? Explain your answer. Individual Genotype(s) possible given the information in the question Charlie Woman Baby Babys father, if not Charlie D-F: SEX-LINKED DISORDERSS - please pay attention to the 2 reminders! REMINDER #1: YOU MUST INCLUDE X and Y IN YOUR GENOTYPES WHEN ANALYZING X-LINKED TRAITS! (See page 176 of the text or the lecture for examples of how to write these genotypes. Do not make up your own format for showing these genotypes!) REMINDER #2: X and Y are NOT included in the genotypes when analyzing disorders that are not sex-linked. D. X-Linked Recessive: Duchenne Muscular Dystrophy I read a case study (true story) of a family who had a son with MD. When the son was first diagnosed with MD the doctor told the mother that "half on any sons she would have might develop MD". He also told her of the likely consequences of the disease as her son grew. She understood him to say that there was no medical treatment available (there is some that would have improved her sons quality of life). She went on the have two more sons, self-diagnosed them to have MD, and did not obtain medical treatment for any of the sons. She has a healthy daughter. Their story came to light soon before her youngest son died. More detailed information on the family follows. Both the woman and her husband are healthy. D1. Create a pedigree for the family in the case study. Shade in the circles/boxes of the individuals with MD. In addition, give as much information as possible about each family member's genotype. If more than one option is possible please show both. Don't forget this is an X-linked disorder. Letter Key: H = healthy h = muscular dystrophy (6 points) D2. What did the physician mean when he/she told the woman that half of any sons she had might develop MD? Was the woman correct in interpreting this as; if she had 4 boys, 2 would be healthy and 2 would have MD? (4 points) D3. Discuss the biological cause of Duchenne muscular dystrophy. Your answer should include the relationship between the DNA, the proteins made, and the symptoms. (4 points) E. X-Linked Recessive: Coloboma Iridis..NO additional research on the disorder is needed to answer this question. Base your answer on the information in the question only. E1. (This one is not a real story. It comes from a genetics textbook) Upon the birth of their first child the husband accuses his wife of being unfaithful. His grounds for this claim are as follows. Both the husband and his wife have normal eyes, yet their daughter has coloboma iridis. Is the husband's claim that he is not the baby's father grounded? Fully support your answer by giving the genotype of the baby, mother, and the husband. In addition, give the genotype of the baby's father if you believe it is not the husband. (6 points) Letter Key: I = normal eyes i = coloboma iridis E2: Fully explain how/if your answer would have been different if the baby had been a son. (4 points) F3: Y-Linked Trait: Hairy Ears! The allele for hairy ears is located on the Y chromosome. No genetic information for this trait is located on the X chromosome. A man with hairy ears is married to a woman without hair in her ears. They have 2 daughters and two sons. Would you expect any of their children to have hairy ears? (Be as specific as possible.) Explain your answer. (4 points) ...
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This note was uploaded on 07/21/2011 for the course BIO 101 taught by Professor Staff during the Spring '08 term at Northern Virginia Community College.

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