Fall -07 answers

Fall -07 answers - Go on to the next page Principles of...

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Unformatted text preview: Go on to the next page Principles of Biology II (2:11) 2:11 Exam 1: Oct. 4, 2007 Answer key 1. In lecture, we pointed out that the centromere of each chromosome remains functionally single up to the beginning of anaphase of the second meiotic division. Using this as an important hint, draw a sequence of diagrams illustrating the chromosomal events in meiosis, in an organism in which the haploid number of chromosomes is 2 (n=2). begin with prophase I of meiosis and end with anaphase II of meiosis. Label the stages, the chromatids and centromeres. For this question, you should omit consideration of crossing over. (6 points) PROPHASE I METAPHASE I METAPHASE II ANAPHASE II chromatid centromere 2:011 Exam 1 Fall 2007 80 pt/ 2 hr 2 Go on to the next page The following five questions refer to the abbreviated Drosophila genetic map illustrated below. The genes considered in the questions are marked by arrows. The mutant alleles to be considered ( vermilion eye, black body, purple eye, cinnabar eye, vestigial wing, sepia eye ) are all recessive. 2. A male with vermilion eyes was crossed with a wild-type female from a pure-breeding stock. The F 1 males from this cross were then testcrossed to vermilion-eyed females. Below, diagram the two successive crosses, giving the genotypes, phenotypes and ratios. Label the sexes as well as the phenotypes of the parents and progeny of each generation. (4 points) P: vY F1 v + Y vv v + v + vermilion wild-type wild-type vermilion vv + 1/2 wild-type females & vY 1/2 vermilion males (you can include combinations of gametes here) 2:011 Exam 1 Fall 2007 80 pt/ 2 hr 3 Go on to the next page 3. A two-factor cross was set up to check the some of the map distances shown in the genetic map. Flies with black bodies (pure-breeding for normal eye color) were crossed with flies with purple eyes (pure-breeding for normal body color). The doubly-heterozygous F1 flies were then testcrossed to flies with black bodies and purple eyes. One thousand progeny of this testcross were scored. List the phenotypic classes that you would expect to obtain from this testcross, and the number of flies (out of the total of one thousand) that you would expect to observe in each class, based on the map distance between the black-body and purple-eye genes shown in the genetic map on p. 3. To get the correct answer, work the problem through carefully, and show your work (5 points) . bbp + p + b + b + pp gametes bp + b + p F 1 bp + b + p parental P black body purple eye bbpp (black-body, purple eye) bp bp bp + b + p bp b + p + parental-type gametes 94% recombinant gametes 6% bp bp bp bp bp + b + p b + p + bp bp bp bp bp black bodied purple eyed wild type black bodies & purple eyed ~47% ~470 ~47% ~470 ~3% ~30 ~3% ~30 2:011 Exam 1 Fall 2007 80 pt/ 2 hr 4 Go on to the next page 4. Suppose now that by making appropriate crosses you have confirmed that the map...
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This note was uploaded on 03/28/2008 for the course BIO 2:11 taught by Professor Frankle during the Fall '07 term at University of Iowa.

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Fall -07 answers - Go on to the next page Principles of...

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