Question

Assortment of genes on same chromosome In the fruit fly Drosophila, there is a dominant gene for normal wings and its recessive allele for vestigial wings. At another gene locus. there is a dominant gene for red eyes and its recessive allele for purple eyes. A female that was heterozygous at both gene loci was mated with a male that is homozygous for both recessive alleles. Knowing this, complete the sentences with the correct terms. 94% crossing over independent assortment on the same chromosome 50% 5% on different chromosomes 25% If you assume that these two allele pairs are located on two different pairs of homologous chromosomes, the expected frequency of flies with normal wings and red eyes in the Fı generation is If you assume that these two allele pairs are located on the same pair of homologous chromosomes (with both dominant alleles on one homologue and both recessive alleles on the other homologue) and no crossing over occurs between them, the expected frequency of flies with normal wings and red eyes in the F1 generation is In this experiment, the mating produced 1,000 flies and 470 have normal wings and red eyes. The observed frequency of flies with normal wings and red eyes in the Fi generation is You examine the Fi offspring from this cross and count the following: 470 normal wings with red eyes 30 vestigial wings with red eyes, 26 normal wings with purple eyes, and 474 vestigial wings with purple eyes. Based on these results, these two gene loci are probably located The genotypes of all or most of the 56 Fifies that have either vestigial wings and red eyes OR normal wings and purple eyes were most likely caused by the process of

Answer 1

ANSWERS;

Assortment of genes on same chromosome n the fruit fly Drosophila, there is a dominant gene for normal wings and its recessive allele for vestigial wings. At anot there is a dominant gene for red eyes and its recessive allele for purple eyes. A female that was heterozygous at both mated with a male that is homozygous for both recessive alleles. Knowing this, complete the sentences with the correc 94% crossing over independent assortment on the same chromosome 50% 47% 5% on different chromosomes 75% 25% If you assume that these two allele pairs are located on two different pairs of homologous chromosomes, the expected frequency of flies with normal wings and red eyes in the Fı generation is 25% If you assume that these two allele pairs are located on the same pair of homologous chromosomes (with both dominant alleles on one homologue and both recessive alleles on the other homologue) and no crossing over occurs between them, the expected frequency of flies with normal wings and red eyes in the Fi generation is 50% In this experiment, the mating produced 1.000 flies and 470 have normal wings and red eyes. The observed frequency of flies with normal wings and red eyes in the F1 generation is 2170 You examine the Fi offspring from this cross and count the following: 470 normal wings with red eyes, 30 vestigial wings with red eyes, 26 normal wings with purple eyes, and 474 vestigial wings with purple eyes. Based on these results, these two gene loci are probably located on the same chromosome The genotypes of all or most of the 56 F. flies that have either vestigial wings and red eyes OR normal wings and purple eyes were most likely caused by the process of crossing over

Explanations : Let the alleles responsible fore type of wings be reepreesented as Vtve, vt dominant allele fore normal wings . v recessive allele fore vestigial wings. Also, let the alleles contreelling eye-colour be represented as pt-p , where pt dominant allele fore reed eyes. e recessive allele for purple eyes. According female male to the question, the genotypes of vtuptp. wupp.

) If the alleles fore different chromosomes, would result in the as follows : Parents : vt ptp 2 genes are beated on then independent assortment production of fi generat x upp vp - Fu: vtpte. Vtupp upp. Normel wings, Normal wings, vestigial wings red eyes. purple eyes. red eyes. (25%). "Cosy) (25%) Nupp. vestig vestigial wings purple eyes (3507). 2) chromosome, If and the no alleles are crossing preesent on over takes same place; - Parents: 1 x ble & i lle (vtpple (app) (50%) (50%)

8) The observed frequency of flies with given genotype - No. of flies with the specific genotype x la Total no. of flies = 4 0 x 100 - 48%. Cams). ans U ournle eyes = 26 2 4) The fi flies produced are as follows Normal wings, Red eyes = 470 2 Parental vestigial wings, purple eyes = 474.9 Noremal wings, purple eyes = Recombinants. Vestigial wings reed eyes = 30. J a Hence, the above flies are produced as a result of crossing over between two genes, beated an the same chromosome Had they been beated on different chreemasones, the natio would have been 1:1:1:1 due to independent assortment 5). The recombinant produced due genetypes must to the process of have been crossing over.