ps2as05

ps2as05 - MIT Department of Biology 7.013: Introductory...

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MIT Department of Biology 7.013: Introductory Biology - Spring 2005 Instructors: Professor Hazel Sive, Professor Tyler Jacks, Dr. Claudette Gardel NAME_______________________________________________________________TA________ 7.013 Spring 2005 Problem Set 2 Solutions FRIDAY February 18, 2004 Problem sets will NOT be accepted late. Question 1 The following family was used to study the transmission of a gene responsible for a rare trait. Since the trait is 'rare', assume that people marrying into the family have 2 normal alleles for the gene of interest in this case. This family was found to carry the rare allele manifesting in the ability to see through walls (“x-Ray vision”). The pedigree for this phenotype follows. 1 2 3 4 5 female male Normal vision x-Ray vision a) What is the most likely mode of inheritance? (Choose from: autosomal dominant, autosomal recessive, X- linked dominant, X-linked recessive, Y-linked dominant, and Y-linked recessive, or mitochondrial inheritance.) autosomal recessive b) Use “R” and “r” for the x- R ay vision alleles. Use the capital letter for the allele conferring the dominant phenotype and include sex chromosomes if appropriate. What is the genotype of individual 2? Rr c) What is the genotype of individual 3? rr d) If individual 4 marries individual 5, what is the probability that their child will be heterozygous at the locus of interest? Show your work. 2/3 chance of being Rr vs RR, X 1/2 probability of giving allele --> producing heterozygote = 1/3 1
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same family carries the rare allele for having 6 fingers. The inheritance pattern follows. The inheritance patterns for both the 6-finger phenotype and x-Ray vision are illustrated in the following pedigree. 1 2 3 4 5 6 fingers x-Ray vision Both x-Ray vision and 6 fingers e) What is the most likely mode of inheritance for the allele causing the 6-finger phenotype? (Choose from: autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, Y-linked dominant, and Y-linked recessive, or mitochondrial inheritance.) Autosomal dominant f) If the genes conferring x-Ray vision and having 6 fingers are linked, what alleles of the two genes are found on each chromosome of individual #1, IF NO recombination occurs,? Use “D” and “d” to describe the alleles of the finger or D igit locus. Use “R” and “r” to describe the alleles of the x- R ay locus. Use the capital letter for the allele conveying the dominant phenotype. Place the alleles for each locus on the chromosomes shown below. Indicate whether the chromosomes below are sex chromosomes.
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ps2as05 - MIT Department of Biology 7.013: Introductory...

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