Zoo/Bot 3333 Genetics Quiz 3 4/3/09 For the answers to the quiz, click here:

1. In Burkitt’s Lymphoma: a) a hybrid MYC protein is produced as a result of a translocation; b) a proto-oncogene is transferred into the immunoglobulin gene cluster and expressed at high levels; c) the drug Gleevec has been approved for treating this disorder; d) all of the above; e) none of the above.

Questions 2-3 pertain to the following: Three strains of Drosophila (Bravo, X-ray, and Zorro) are obtained that are homozygous for three variant forms of a particular chromosome. When examined in salivary gland polytene chromosome spreads, all chromosomes have the same number of bands in all three strains. When genetic mapping is performed in the Bravo strain, the following map is obtained (distances in map units). a b c d e f g h 5.8 6.2 3.2 5.7 4.4 7.1 3.2

Bravo and X-ray flies are now mated to form Bravo/X- Gene Intervals Bravo/X-ray Bravo/Zorro ray F1 progeny, and Bravo flies are also mated with a-b 5.8 5.8 Zorro flies to form Bravo/Zorro Fj progeny. In b-c 6.2 0.7 subsequent crosses, the genetic distances on the right c-d 0.2 <0.1 were found to separate the various genes in the hybrids: d-e <0.1 <0.1 e-f <0.1 <0.1 2. Which of the following is the most likely explanation f-g 0.65 0.7 for the differences between the strains? g-h 3.2 3.2 a) reciprocal translocations have occurred, giving rise to balanced translocation heterozygotes; b) inversions have occurred suppressing crossing over; c) deletions have occurred in two different regions of the chromosome; d) duplications have occurred in two different regions of the chromosome; e) a chromosomal deletion has occurred in one strain and a duplication has occurred in the other strain.

3. In the original X-ray homozygous strain, which of the following statements are true? a) a and c are closer than in the Bravo strain; b) c and d are closer than in the Bravo strain; c) c and f are closer than in the Zorro strain; d) all of the above; e) none of the above.

4. Deletions can be used to determine the orientation of genes on a chromosome. A series of 5 deletions "uncovered" the following recessive mutations in deletion heterozygotes, allowing them to show pseudodominance (see text 496 3e): deletion 1: o, p, n deletion 2: n, p deletion 3: k, l, o deletion 4: m, n, p deletion 5: l, n, o

Which of the following gene orders is consistent with a deletion map of this area? a) npoklm; b) ponkol; c) klopnm; d) klonpm; e) more than one solution is possible.

5. During ascus formation in Neurospora, any ascospore with a chromosomal deletion dies and appears white in color. How many ascospores of the eight spores in the ascus would be white if the octad came from a cross of a wild-type strain with a strain of the opposite mating type carrying a reciprocal translocation, and an adjacent-1 segregation occurred with no crossovers between translocated chromosomes? a) none; b) 2; c) 4; d) 6; e) 8.

Questions 6-7 pertain to the following. An Hfr strain of the genotype a+b+c+d+strs is mated with a female strain of the genotype a−b−c−d−strr. At various times the culture is disrupted in a blender to separate the mating pairs. The cells are then plated on agar of the following four agar types (see table below, right), where nutrient A allows the growth of a− auxotrophs, nutrient B allows for the growth of b− autxotrophs, etc. As indicated, all types contain streptomycin (Str). A (+) indicates the presence of the nutrient or drug, a (-) indicates its absence. Agar Type Str A B C D Timings of Samples Number of Colonies of Agar of Type 1 + + − + + 1 2 3 4 2 + − + + + 0 0 0 0 0 3 + + + + − 4 + + + − + 2.5 0 4 0 0 5 5 60 0 0 7.5 60 132 0 0 10 98 220 0 0 12.5 127 315 0 6 15 153 370 0 67 17.5 170 398 4 104 20 190 414 35 125 25 205 416 40 138 30 210 420 42 140 The table above shows the number of 35 215 425 48 142 colonies on each type of agar for samples taken at various times after the samples are mixed:

6. From the gene closest to the origin of replication, the order of the genes is: a) a b c d; b) b a c d; c) c a b d; d) d c b a; e) none of the above

7. True or false. On the basis of this data, gene b is closer to a than it is to d.

8. In a cross between an Hfr that has the genotype x+y+z+ and an F– that is x–y–z–, the x x+y+z+ 220 gene is known to be transferred later than y and z. To determine the order of y and z with x+y–z– 60 + respect to x, x exconjugants are selected and screen for their y and z phenotypes. The x+y–z+ 18 results of these tests are listed in the chart on the right: x+y+z– 0 These results indicate: a) that z is between x and y; b) that the distance between x and z is much smaller than the distance between x and y; c) that z is closer to the F factor origin than y; d) all of the above; e) none of the above.

Questions 9-10 pertain to the following You have infected E. coli cells m r tu 3467 m + 520 with two strains of T4 virus. One strain is minute (m), rapid lysis (r), + and turbid (tu); the other is wild type for all three markers. The lytic + + + 3729 + r tu 474 products of this infection are plated and classified. The resulting 10,342 plaques were distributed among eight genotypes, as follows: m r + 853 + r + 172 m + 162 + + 965 9. From this data set, the order of the gene loci is: tu tu a) m r tu; b) r m tu; c) m tu r; d) it is impossible to calculate from this data set.

10. On the basis of this data set, a map distance between the m and r genes can be calculated as: a) 12.8 map units; b) 20.8 map units; c) 27.2 map units; d) 46.5 map units; e) none of the above.