a. In Drosophila, crosses between F1 heterozygotes of the form A b / a B always yield the same ratio of
b. If you intercrossed F1 heterozygotes of the form A b / a B in mice, the phenotypic ratio among the F2 progeny would vary with the map distance between the two genes. Is there a simple way to estimate the map distance based on the frequencies of the F2 phenotypes, assuming rates of recombination are equal in males and females? Could you estimate map distances in the same way if the mouse F1 heterozygotes were A B / a b?
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- In Drosophila melanogaster, red eyes are dominant over white and the variation for this characteristic is on the X chromosome. Vestigial wings (v) are recessive to normal (V) for an autosomal gene. Predict the appearance of offspring of the following crosses: XW/Xw V/v×Xw/Y v/v, Xw/Xw V/v × XW/Y V/v.arrow_forwardMonohybrid Cross: 1) In dogs, wire hair (S) is dominant to smooth (s). a. In a cross between a homozygous wire-haired dog with a smooth haired dog what are the genotypes and phenotypes of the F1 generation? b. If a brother and sister from the F1 generation are crossed what is the expected ratio of wire-haired to smooth-haired dogs produced from this cross?arrow_forwardIn Drosophila melanogaster, red eyes are dominant over white and the variation for this characteristic is on the X chromosome. Vestigial wings (v) are recessive to normal (V) for an autosomal gene. Predict the appearance of offspring of the following crosses: XW/XwV/v×Xw/Y v/v, Xw/XwV/v×XW/Y V/v.arrow_forward
- a. In a type of plant, pink flowers (P) is dominant over white flowers (p), and tall (T) is dominant over short (t). Determine the genotypes of the parents in the following cross: Pink, tall x pink, short O / pink, tall: /s pink, short: /s white, tall: / white, short Genotypes: () (ii) Phenotypes: Pink, tall Pink, short b. A woman has blood type A MM. She has a child with blood type O MN. Which of the following men could not be the child's father? Explain your reasoning. Man Blood type Peter O NN Rob AB MN Doug B MN Simon A NN Mike АВ Мarrow_forwardIN DROSOPHILA, AN X-LINKED RECESSIVE MUTATION, Xm CAUSES MINIATURE WINGS. LIST THE F₂ PHENOTYPIC RATIOS IF: A MINIATURE-WINGED FEMALE IS CROSSED WITH A NORMAL MALE AND A MINIATURE-WINGED MALE IS ● ● CROSSED WITH A NORMAL FEMALE. WHAT WOULD THE PHENOTYPIC RATIO FROM (A) BE IF THE MINIATURE- WINGED GENE WERE AUTOSOMAL? ASSUME IN ALL CASES THAT THE P1 INDIVIDUALS ARE TRUE-BREEDING.arrow_forwardDeranged: is a phenotype in Drosophila in which the thoracic bristles are disarranged and the wings held vertically upward. Crosses between deranged females and normal males, each from pure stock cultures, result in a 1:1 ratio of normal females to deranged males among the progeny. What does this show? A. The gene for deranged is autosomal and dominant. B. The gene for deranged is autosomal and recessive. C. The gene for deranged is X-linked and dominant. D. The gene for deranged is X-linked and recessive. E. Deranged is determined by two genes interacting epistatically.arrow_forward
- I. Assume that there is no interference in the Lf-W region. The cross between the triple heterozygote (Lf J W/ lf j w) and a triple homozygous recessive produced 375 progenies. Give the frequency of each specific progeny type: a. with crossover in the Lf-J and J-W regions b. with crossover in the Lf-J region c. with crossover in the J-W region d. without crossover in the Lf-W region II. Assume that there is complete interference in the Lf-W region. The cross between the triple heterozygote (Lf J W/ lf j w) and a triple homozygous recessive produced 350 progenies. Give the frequency of each specific progeny type: a. with crossover in the Lf-J and J-W regions b. with crossover in the Lf-J region c. with crossover in the J-W region d. without crossover in the Lf-W regionarrow_forwardA mutant sex-linked trait called “notched” (N) is deadly in Drosophila when homozygous in females. Males who have a single N allele will also die. The heterozygous condition (Nn) causes small notches on the wing. The normal condition in both male and females is represented by the allele n. a) Indicate the phenotypes of the F1 generation from the following cross: XNXn x XnY b) Explain why dead females are never found in the F1 generation no matter which parents are crossed. c) Explain why the mating of female XNXn and a male XNy is unlikely.arrow_forwardI. Male Drosophila from a true-breeding wild-typestock were irradiated with X-rays and then mated withfemales from a true-breeding stock carrying the following recessive mutations on the X chromosome:yellow body (y), crossveinless wings (cv), cut wings(ct), singed bristles (sn), and miniature wings (m).These markers are known to map in the order:y - cv - ct - sn - mMost of the female progeny of this cross were phenotypically wild type, but one female exhibited ct and snphenotypes. When this exceptional ct sn female wasmated with a male from the true-breeding wild-typestock, twice as many females as males appearedamong the progeny.a. What is the nature of the X-ray-induced mutationpresent in the exceptional female?b. Draw the X chromosomes present in the exceptional ct sn female as they would appear duringpairing in meiosis.c. What phenotypic classes would you expect to seeamong the progeny produced by mating the exceptional ct sn female with a normal male from a truebreeding wild-type…arrow_forward
- DIHYBRID CROSS: In rabbits, assume that spotted skin (G) is dominant over non-spotted skin (g) and that wooly hair (B) is dominant over nonwooly hair (b). Cross a marriage between a male rabbit with the genotype GGBB with a female rabbit with the genotype ggbb. Show the P1, F1, P2 and F2 generation on a Punnett Square. Give the genotypic and phenotypic ratio of the offspring and the tally of genotype and phenotype of the offspring.arrow_forwardConsider the following crosses in Drosophila. The two traits being investigated involve eye color and the presence or absence of wing crossveins. The outcomes of four crosses are shown below.›arrow_forwardIn Drosophila melanogaster white (w) and miniature (m) wings are controlled by X-linked recessive genes with a recombination fruequency between them of approximately 38%. Show the sexes, phenotypes and proportions of offspring expected from the following mating:a. ++/wm female X wm maleb. +m/w+ female X w+ malec. w+/+m female X ++ maleIf we assume that white eyes and miniature wings are not x-linked but are linkedto the autosomal genes, what phenotypic frequencies would you expect from this cross: ++/wm female X ++/wm male?arrow_forward
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