gene final

gene final - GENE 3200 Summer 2010 Bedell Final exam July...

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GENE 3200 – Summer 2010 – Bedell Final exam – July 30 ID no. 810__________ KEY ________________ 1 Write your ID number (810 number, NOT SSN) on every page. Write your initials on the first page only. All of the multiple choice questions have only one correct answer. The exam should be completed in ink. Regrades will not be given if you write in pencil. All requests to re-grade an exam must be made in writing to Dr. Bedell within 48 hours of the grades being posted on WebCT. Class average was 116/150 (77%) 1. (1 pt) True or false. For two unlinked genes A and B , the phenotypic ratios in progeny of AA bb x aa BB will be 1:1:1:1. (assume complete dominance ) 2. (2 pts) Calculate the probability of the production of a homozygous recessive genotype for the following cross: Aa Bb cc dd Ee ! Aa Bb Cc dd ee 1/4 ! 1/4 ! 1/2 ! 1 ! 1/2 = 1/64 or 0.0156 3. In Drosophila, two autosomal genes are known to control wingsize and eye shape. For wingsize, t is the recessive allele for tiny wings and T is the dominant allele for normal wing size. For eye shape, n is the recessive allele for narrow eyes and N is the dominant allele for oval eyes. A male with normal wings and narrow eyes was crossed to a female with normal wings and oval eyes. The offspring of this course were: normal wings, oval eyes 35 normal wings, narrow eyes 29 tiny wings, oval eyes 10 tiny wings, narrow eyes 11 3 (cont). (3 pts) What are the genotypes of the parents? Give a brief justification for your answer. Male Tt nn x female Tt Nn 3:1 segregation for normal (35 + 29) vs tiny wings (10 + 11), both parents have to be hets; 1:1 segregation for oval (35 + 10) vs narrow eyes (29 + 11) so male is homozygous recessive x female heterozygous 4. At the right is a pedigree for a recessive human trait (use R for the dominant allele and r for the recessive allele). Individuals I-1 and II-4 are known to be R/R but you should NOT make any assumptions about whether this is a rare or common trait (i.e. unrelated individuals may be carriers of the trait). You can assume complete penetrance. 4 (cont) (4 pts) . What is the probability that IV-1 will exhibit the trait? Show all of your calculations. On the pedigree or in the space below, write the genotype and probability for each individual needed to calculate the total probability for IV-1. III-3, 1/2; III-4, 2/3; IV-1, 1/4 1/2 x 2/3 x 1/4 = 2/24 = 1/12
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GENE 3200 – Summer 2010 – Bedell Final exam – July 30 ID no. 810__________ KEY ________________ 2 5. (2 pts) Which of the following is a fundamental difference between epistasis and dominance? A. Epistasis occurs between 2 genes while dominance occurs between alleles of 1 gene. B. Only epistasis is influenced by environmental interactions. C.
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gene final - GENE 3200 Summer 2010 Bedell Final exam July...

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