1. Go to the following


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Go to the following website (http://www.mhhe.com/biosci/genbio/virtual_labs_2K8/pages/LinkedTrait.html). Read and follow the instructions on the left side of the screen. Use this document to record your Table Data as well as answer the Journal Questions. (Click “File, Save As” to save and use this document.) When you have completed the Table Data and answered the Journal Questions, you will need to upload this saved file to blackboard. Fill out in a different font color or you will not receive credit for this assignment. Lab Questions: In a mating between a red-eyed male fruit fly and a red-eyed heterozygous female, what percentage of the female offspring is expected to be carriers? How did you determine the percentage? In a mating between a red-eyed male fruit fly and a white-eyed female fruit fly, what percentage of the male offspring will have white eyes? Describe how you determined the percentage. Hemophilia, a blood disorder in humans, results from a sex-linked recessive allele. Suppose that a daughter of a mother without the allele and a father with the allele marries a man with hemophilia. What is the probability that the daughter’s children will develop the disease? Describe how you determined the probability. Colorblindness results from a sex-linked recessive allele. Determine the genotypes of the offspring that result from a cross between a color-blind male and a homozygous female who has normal vision. Describe how you determined the genotypes of the offspring. Explain why sex-linked traits appear more often in males than in females. In humans, hemophilia is a sex-linked recessive trait. It is located on the X chromosome. Remember that the human female genotype is XX and the male genotype is XY. Suppose that a daughter of a mother without the allele and a father with the allele marries a man with hemophilia. What is the probability that the daughter’s children will develop the disease? Describe how you determined the probability. Colorblindness also results from a sex-linked recessive allele on the X chromosome in humans. Determine the genotypes of the offspring that result from a cross between a color-blind male and a homozygous female who has normal vision. Describe how you determined the genotypes of the offspring. Based on the traits explained in questions 6 and 7, explain why sex-linked traits in humans appear more often in males than in females. Virtual Lab: Sex-Linked Traits Worksheet Please make sure you have read through all of the information in the “Questions” and “Information” areas. If you come upon terms that are unfamiliar to you, please refer to your textbook for further explanation or search the word here: http://encarta.msn.com/encnet/features/dictionary/dictionaryhome.aspx Next, complete the Punnett square activity by clicking on the laboratory notebook. Please be sure to note the possible genotypes of the various flies: Female, red eyes Female, red eyes Female, white eyes Male, red eyes Male, white eyes When you have completed the Punnett square activity, return to the laboratory scene to begin the actual laboratory activity. In this exercise, you will perform a Drosophila mating in order to observe sex-linked trait transmission. Please click on the shelf in the laboratory. Here you will find vials of fruit flies. On the TOP shelf, please click on one of the female vials (on the left side) and then drag it to the empty vial on the shelf below. Please repeat this step using one of the male vials (on the right side). These flies will be used as the parental (P) generation. You may switch your parent choices at any time by dragging out old selections and dragging in new flies. Use the Punnett square below to predict the genotypes/phenotypes of the offspring (Note: refer to the genotype table you created above if needed): Genotype: Phenotype: Genotype: Phenotype: Genotype: Phenotype: Genotype: Phenotype: ___% Female, red eye ___% Female, white eye ___% Male, red eye ___% Male, white eye When you are

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