Concept explainers
In tomatoes, the allele
fruit is dominant to the recessive
A
What are the genotype and phenotype of the
What are the genotypes of gametes produced by the
The
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- In a certain plant, leaf size is determined by fourgenes whose alleles assort independently and actadditively. Thus, alleles A, B, C, and D each add4 cm to leaf length and alleles A′, B′, C′, andD′ each add 2 cm to leaf length. Therefore,an AA BB CC DD plant has leaves 32 cm longand an A′A′ B′B′ C′C′ D′D′ plant has leaves16 cm long.a. If true-breeding plants with leaves 32 cm longare crossed to true-breeding plants with leaves16 cm long, the F1 will have leaves 24 cm longand the genotype AA′ BB′ CC′ DD′. Listall possible leaf lengths and their expectedfrequencies in the F2 generation produced fromthese F1 plants.arrow_forwardYou are working with a hypothetical fly and have found color and wing mutants. Preliminary work indicates that the mutant traits are recessive and the associated genes are not sex-linked, but beyond that, you have no information. You first look at 2 genes, each with 2 alleles. "B" or “b" for body color and "W" or "w" for wing surface. The red-body phenotype is dominant to the yellow-body phenotype and smooth wings are dominant to crinkled wings.arrow_forwardA yeast geneticist irradiates haploid cells of a strain that is an adenine-requiring auxotrophic mutant, caused by mutation of the gene ade1. Millions of the irradiated cells are plated on minimal medium, and a small number of cells divide and produce prototrophic colonies. These colonies are crossed individually with a wildtype strain. Two types of results are obtained:(1) prototroph × wild type : progeny all prototrophic(2) prototroph × wild type : progeny 75% prototrophic, 25% adenine-requiring auxotrophsa. Explain the difference between these two types of results.b. Write the genotypes of the prototrophs in each case.c. What progeny phenotypes and ratios do you predict from crossing a prototroph of type 2 by the original ade1auxotroph?arrow_forward
- Drosophila females heterozygous for 3 recessive mutations a, b, and c werecrossed to males homozygous for all 3 mutations. The cross had the followingresults:wild 75 c 348 ab 306b 96 ac 110 abc 85Based on their recombination frequencies, the map distances in cM among the 3alleles are? a-b ; b-c ; a-c?arrow_forwardRecombination frequencies between four genetically-linked loci in corn are shown in the following table: Loci Recombination Frequency (%) L and Q 20 Q and R 50 R and L 30 Q and W 13 L and W 7 What is the order of the genes on the chromosome? (note: The same answer can be represented forward or backwards. e.g. A B C D = D C B A) LQWR RQWL LRQW QRLW RLWQarrow_forwardYou are mapping three linked loci in Drosophila melanogaster (the common laboratory fruit fly). You cross flies that are triply mutant for apricot (pale eyes), bristle (extra bristles) and clipped (notched wings) to wild-type flies. The F+ flies are wild-type in appearance. You then backcross the F+ females to pure-breeding (apricot, bristle, clipped) males and score the phenotypes of 1000 F progeny for all three loci. Here are the results: 359 wild-type 361 apricot, bristle, clipped 89 bristle, clipped 91 apricot 42 apricot, bristle 38 clipped 9 apricot, clipped 11 bristle Using these data, first determine what gametes from the F; trihybrid produced each of the eight F2 categories. Note that apricot = aa (recessive to wild-type A); bristle = bb (recessive to wild-type B); and clipped = cc (recessive to wild-type C). Then determine if each gamete is recombinant (R) or nonrecombinant (R) for each pair of alleles (that is, for each genetic interval). Complete the table by dragging the…arrow_forward
- The following recombinant frequencies were found between genes A, B, C, D, and E. Determine the order of these genes on the chromosome and draw a linkage map of this chromosome with the map units labeled. А, С: 10% А, D: 30% А, Е: 6% В, С: 4% В, D: 16% В, Е: 20% C, D: 20%arrow_forwardSemisterility in corn, as seen by unfilled ears withgaps due to abortion of approximately half the ovules,is an indication that the strain is a translocation heterozygote. The chromosomes involved in the translocation can be identified by crossing the translocationheterozygote to a strain homozygous recessive for agene on the chromosome being tested. The ratio ofphenotypic classes produced from crossing semisterileF1 progeny back to a homozygous recessive plant indicates whether the gene is on one of the chromosomesinvolved in the translocation. For example, a semisterilestrain could be crossed to a strain homozygous for the yg mutation on chromosome 9. (The mutant has yellowgreen leaves instead of the wild-type green leaves.) Thesemisterile F1 progeny would then be backcrossed tothe homozygous yg mutant.a. What types of progeny (fertile or semisterile, greenor yellow-green) would you predict from the backcross of the F1 to the homozygous yg mutant if thegene was not on one of the two…arrow_forwardIn the fruit fly, dumpy wings (d) and purple eyes (p) are encoded by mutant alleles that are recessive to those that produce wild type traits; long wings (d+) and red eyes (p+). These two genes are on the same chromosome. In a particular lab, two researchers Walt and Jesse crossed a fly homozygous for dumpy wings and purple eyes with a fly homozygous for the wild type traits. The F1 progeny, which had long wings and red eyes, was then crossed with flies that had dumpy wings and purple eyes. Unfortunately, the progeny of this cross somehow escaped. To prevent their other projects from contamination, they decided to spend an exceptionally boring hour in the lab catching and counting the progeny and found the following: long wings, red eyes – 482 dumpy wings, purple eyes – 473 long wings, purple eyes – 23 dumpy wings, red eyes - 22 What is the genetic distance between these two loci? a. 4.5 cM b. 55 cM c. 45 cM d. 49.5 cM e. 4.7 cMarrow_forward
- Wild-type mice have brown fur and short tails. Loss of function of a particular gene produces white fur, while loss of function of another gene produces long tails, and loss of function at a third locus produces agitated behavior. Each of these loss of function alleles is recessive. If a wild-type mouse is crossed with a triple mutant, and their F1 progeny is test-crossed, the following recombination frequencies are observed among their progeny. Produce a genetic map for these loci. Brown, short tailed, normal: 955 White, short tailed, normal: 16 Brown, short tailed, agitated: 0 White, short tailed, agitated: 36 Brown, long tailed, normal: White, long tailed, normal: Brown, long tailed, agitated: 46 0 14 White, long tailed, agitated: 933arrow_forwardIn Drosophila (fruit flies), pink eyes (P), curled wings (C), a hairy body (H), and an ebony body (E) are determined by genes located on the same chromosome. Gene Combination Recombination Frequency E/H 41.7% C/H 18.2% E/P 22% H/P 19.7% Which of the following gene maps shows the gene sequence on this chromosome?arrow_forwardBranch length in the plant Karlheinz rummeniggeus is under polygenic control. The phenotype exhibits continuous variation. Branches can be absent, 1, 2, 3, 4, 5, 6, 7, or 8 m long. How many different genotypes encode a plant with branches that have a length of exactly 7 m? 3 4 5 7 B Atte 35arrow_forward
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