Molecular Genetics Chap 7

Genes A, B, and C are linked. Crossover gametes between A and B are recovered 15% of the time and crossovers B and C 10% of the time. What percentage of double crossovers is expected between A B and C?

1.5%

Assume that a cross is made between AaBb and aabb plants and all the offspring are either AaBb or aabb. These results are consistent with the following circumstance

100% complete linkage

A fruitfly that is heterozygous for the brown eye (bw) and heavy wing vein (hv) genes is test-crossed to a homozygous brown eyed, heavy winged fruitfly. If the bw and hv genes are completely linked then the ratio of offspring will be.... (Assume that the recessive alleles are both on the same chromosome)

1:1 heavy brown: thin red

In the previous question, if the bw and hv genes are not linked then the ratio of offspring will be:

1:1:1:1 heavy red: heavy brown: thin red: thin brown

In cross where alleles of two genes are on the same chromosome are followed, the frequency of non-parental genotypes (crossovers) is 29%. The distance between the two genes in map units is:

29 map units

The genes for mahogany eyes and ebony body are approximately 30 map units apart on chromosome III in Drosophila. Assume that a mahogany-eyed female was mated to an ebony-bodied male and the resulting F1 phenotypically wild type females were mated to mahogany, ebony males. Of 1,000 offspring, what would be the expected phenotypes and in what numbers would they be expected?

350 mahogany, 350 ebony, 150 wild type, 150 mahogany ebony

The genes for mahagony eyes and ebony body are approximately 25 map units apart on the chromosome III in drasophila. Assume that a mahogany-eyed female was mated to an ebony-bodied male and the resulting F1 phenotypically wild trype females were mated to mahogany, ebony males. Of 1,000 offspring, what would be the expected phenotypes and in what members would they be expected?

375 mahogany, 375 ebony, 125 wild type, 125 mahogany-ebony

Assume that the genes for tan body(t) and bare wings(b) are 15 map units apart on chromosome II in Drosophila. Assume also that a tan-bodied, bare-winged female (tb) was mated to a wild type male (++ or TB) and the resulting F1 phenotypically wild type females were mated to tan-bodied, bare- winged males. Of 1000 offspring, what would be the expected phenotypes and in what numbers would they be expected?

425 wild type, 425 tan-bare, 75 tan, 75 bare

What is the largest possible fraction of recombinants in the final gametes for single crossover events?

50%

Which of the following progeny would represent a double crossover progeny class from the cross AbC/aBc X abc/abc?

ABC/abc or abc/abc

Which of the following progeny would represent a single crossover progeny class form the cross AbC/aBc X abc/abc?

Abc/abc

Assume that a cross is made between AaBb and aabb animals and the offspring occur in the following numbers: 106 Aabb, 48 AaBb, 52 aabb, 94 aaBb. These results are consistent with the following arrangements of gense:

In the AaBb parent, the A allele is on the same chromosome as the b allele or In the AaBb parent, the B allele is on the same chromosome as the a allele.

Assume that a cross is made between AaBb and aabb plants and the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with the following arrangement of genes

In the AaBb parent, the dominant genes are on one homologue and the recessive genes are on the other

William Bateson and Reginald Punnett were interested in trait inheritance in the sweet pea and were studying two linked genes—the gene for flower color (P, purple, and p, red) and the gene affecting the shape of pollen grains (L, long, and l, round). They crossed the pure lines PPLL and ppll to produce the dihybrid. Which of the following gametes would be produced in the highest proportion by the F1 dihybrid plants?

PL

Use the following information for this question. The distances between genes A, B, C and D are A-B= 5 map units, B-C= 10 map units and C-D= 23 map units. The genes are arranged in the order -A-B-C-D- on the chromosome. What would be the genotype of the progeny expected to be found in the lowest percentage from the test cross of an individual who is BcD/bCd?

bcd/bcd

Crossing over refers to exchange of genetic information __________

between nonsister chromatids

Assume that a cross is made between AaBb and aabb plants and all the offspring are eeither AaBb or aabb. These results are consistent with the following circumstance

complete linkage

When two genes fail to assort independently the term normally applied is

linkage

Assume that a cross is made between AaBb and aabb plants and the offspring occur in the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with the following circumstance:

linkage with approximately 33 map units between two gene loci

Genes that are found on the same chromosome are said to be

linked

In a three-point mapping experiment, what three general classes of offspring are expected (assuming crossovers occur)?

non-crossovers, single crossovers, double crossovers

In a three-point mapping experiment, what general classes of offspring are expected (assuming crossovers occur)?

noncrossovers, single crossovers and double crossovers

To what scientific activity does the tern synkaryon refer?

nuclear fusion and gene mapping in eukaryotes

Complete linkage results in the production of only

parental gametes

The linked recessive gense sm and px in Drasophila melanogaster code for smooth abdomen and plexus wings respectively. True breeding wild type flies are mated with smooth-abdomen, plexus-winged flies to produced the dihybrid. Which of the following gametes would be produced in the highest proportion by the F1 dihybrid flies?

sm+px+

The non-crossover phenotypes in a three point crossing experiment are generally easily identified because they correspond to:

the most numerous events

Single crossover events are only detectable if ____________

they occur between the linked genes under consideration

t/f The cross GE/ge X ge/ge produces the following progeny, GE/get 404; ge/ge 396; gE/ge 97; Ge/ge 103. From these data one can conclude that the recombinant progeny are gE/ge and Ge/ge.

true

Female frutiflies that are heterozygous for the linked genes yellow body color (y), white eye color (w) and echinus eye shape (ec) are crossed to males that are y,w,ec. The numbers of offspring with various phenotypic combinations are as follows: (in this question assume that the female has all the recessive genes on one homolog and all the wild-type genes on the other. y w ec 4685 y+ w+ ec+ 4759 y w+ ec+ 80 y+ w ec 70 y w ec+ 193 y+ w+ ec 207 y w+ ec 3 y+ w ec+ 3

y w ec