Zoo/Bot 3333
Genetics
Quiz #3
10/29/10
For answers to the quiz, click here:
1. Please consider the deletion mapping experiment described for this region of a polytene chromosome of Drosophila.
Four deletions are isolated that remove the parts of this chromosome indicated below and that allow expression of the recessive gene “x” when heterozygous for the specified deletion and a chromosome carrying a recessive x allele. Assume the chromosome map continues to the left and to the right following the same nomenclature.
Deletion 1: 30E6 – 31C3
Deletion 2: 31B5 – 32B5
Deletion 3: 31B1 – 32A1
Deletion 4: 30F5 – 31C1
Which interval provides the most accurate mapping of the x gene?
a) 30E6–31B3; b) 30F5 – 32B5; c) 31B1 – 32A1; d) 30F5 – 31C1; e) 31B5 – 31C1
a / b / c / d / e / fDeletion 1 / - / - / - / + / + / +
Deletion 2 / - / - / + / + / + / +
Deletion 3 / - / - / + / - / + / +
Deletion 4 / + / - / + / - / + / -
Deletion 5 / + / + / + / - / - / -
2. Recessive alleles a, b, c, d, e, and f are known to be contiguous in the genome, but their order is unknown. When the following deletions are heterozygous with each mutant allele, the results indicated in the chart are obtained, where (+) indicates a wild type phenotype, and a (-) indicates a mutant phenotype:
The order of these genes in relation to one another is:
a) efdbac; b) decfab; c) cabfde; d) bacedf; e) none of the above.
3. If a plant of species B (2n = 44) is combined with species T (2n = 18) to produce an amphidiploid allopolyploid, the new species will have how many linkage groups?
a) 18; b) 31; c) 44; d) 62; e) 124.
4. There are two species of midge which occupy the same geographical area (i.e. are sympatric). During meiosis, it can be seen that each species has six pairs of chromo-somes. The two species will hybridize, and when meiotic prophase 1 chromosomes in the hybrid are examined, one sees the formation of 4 bivalents and one tetravalent. This result is best explained by:
a) a reciprocal translocation; b) a chromosome inversion; c) a chromosomal deletion;
d) allopolyploidy; e) nullisomy.
5. In Burkitt’s lymphoma:
a) a chromosomal translocation in B cells leads to uncontrolled growth; b) the myc gene is turned on inappropriately; c) the normal maturation process leading to antibody diversity has functioned inappropriately; d) all of the above; e) none of the above.
Questions 6-8 pertain to the following. Mr. and Mrs. Simpson have not yet been able to produce a viable child. They have had two miscarriages that occurred very early during pregnancy, and one child who died in utero at approximately 7 months. Studies of the banded chromosomes of mother, father and fetus showed no differences in the karyotypes- with the exception of chromosome 6, shown below:
6. The shortened chromosome six observed in the fetus:
a) was derived from the father; b) was derived from the mother; c) was generated during the fetus’ development; d) a, b or c are equally likely; e) was derived from neither karyotype, indicating a case of questionable paternity.
7. The shortened chromosome six observed in the fetus:
a) is duplicated for some genes normally on six; b) is deficient for some genes normally on six; c) has picked up some genes from another chromosome; d) both a and b are correct; e) none of the above.
8. True or false: Due to the nature of the karyotypes shown here, there is no chance that this couple will be able to have a normal child.
9. Which of the following may result in oncogenesis (cancer)?
a) chromosomal deletion; b) reciprocal translocation; c) point mutation; d) viral infection; e) all of the above.
10. In 1946, Lederberg and Tatum performed an experiment demonstrating genetic exchange in bacteria. This experiment required:
a) cell-cell contact; b) ability to grow on streptomycin; c) bidirectional genetic transfer between two compatible strains; d) all of the above; e) none of the above.
.