Concept explainers
In pigs, coat color may be sandy, red, or white. A geneticist spent several years mating true-breeding pigs of all different color combinations, even obtaining true-breeding lines from different parts of the country. For crosses 1 and 4 in the following table, she encountered a major problem: her computer crashed and she lost the F2 data. She nevertheless persevered and, using the limited data shown here, was able to predict the mode of inheritance and the number of genes involved, as well as to assign genotypes to each coat color. Attempt to duplicate her analysis, based on the available data generated from the crosses shown.
Cross | P1 | F1 | F2 |
1 | sandy
|
All red | Data lost |
2 | red
|
All red | 3/4 red: 1/4 sandy |
3 | sandy
|
All sandy | 3/4 sandy: 1/4 white |
4 | white
|
All red | Data lost |
When you have formulated a hypothesis to explain the mode of inheritance and assigned genotypes to the respective coat colors, predict the outcomes of the F2 generations where the data were lost.
Trending nowThis is a popular solution!
Chapter 4 Solutions
Essentials of Genetics (9th Edition) - Standalone book
- You carry out a trihybrid cross (a cross in which the parental plants differ for three characters) between a tall pea plant with round, yellow seeds (TT RR YY) and a short pea plant with wrinkled, green seeds (tt rr yy). The parental plants are homozygous for all of the three characters. They are crossed to produce the F1 generation. Tall, round, and yellow are the dominant traits for each character. What will be the phenotypes of the F1 generation?arrow_forwardA geneticist has two true-breeding strains of mice. Each strain is homozygous for an independently discovered dominant mutation that causes the mice to have no fur. One mutant strain is called “hairless”, and the other strain is called “naked”. The geneticist crosses hairless and naked mice with each other and the F1 offspring all have no fur. When the F1 mice are crossed with each other, the offspring consist of 187 mutant mice with without fur and 13 normal mice with fur. a. Are the “hairless” and “naked” mutations alleles of the same gene? Give a reason for your answer. b. Give the genotypic and associated phenotypic ratios of the F2 offspring. (which genotypes in the offspring of the F1 x F1 cross produce fur and which genotypes produce no fur). In another strain of mice, coat colour is controlled by a single gene with multiple alleles in a dominance series where cream (A1) > agouti (A2) > brown (A3) > black (A4). c. Give the genotypes of two phenotypically…arrow_forwardA true-breeding purple-leafed plant isolated from one side of El Yunque, the rain forest in Puerto Rico, was crossed to a truebreeding white variety found on the other side. The F1 offspring were all purple. A large number of F1 * F1 crosses produced the following results: purple: 4219 white: 5781 (Total = 10,000) Propose an explanation for the inheritance of leaf color. As a geneticist, how might you go about testing your hypothesis? Describe the genetic experiments that you would conductarrow_forward
- Coat color in mice is influenced by two genes, one for color (A) and one for the amount of pigment production (C). Mice with the wild type agouti coat color have a yellowish to brownish color. Mice also have a gene that determines the amount of pigment the hair produces. Multiple crosses were made between male and female mice that were each heterozygous for both traits (AaCc). The data table shows the number of mice of each coat type. Calculate the average F1 generation coat color to answer the question. Which of the following is the most probable interaction between the two genetic loci, A and C, based on the average F1 ratio results? A - The two loci show an epistatic pattern with the loci C epistatic to loci A.B - The two loci show a codominant pattern with both loci affecting coat color.C - The two loci interact in a Mendelian pattern with A being completely dominant over C.D - The two loci show an incomplete dominance pattern with neither loci A nor C being dominant.arrow_forwardCoat color in mice is influenced by two genes, one for color (A) and one for the amount of pigment production (C). Mice with the wild type agouti coat color have a yellowish to brownish color. Mice also have a gene that determines the amount of pigment the hair produces. Multiple crosses were made between male and female mice that were each heterozygous for both traits (AaCc). The data table shows the number of mice of each coat type. Calculate the average F1 generation coat color to answer the question. Which of the following is the most probable interaction between the two genetic loci, A and C, based on the average F1 ratio results? A - The two loci show an epistatic pattern with the loci C epistatic to loci A. B - The two loci show a codominant pattern with both loci affecting coat color. C - The two loci interact in a Mendelian pattern with A being completely dominant over C. D - The two loci show an incomplete dominance pattern with neither loci A nor C being dominant.arrow_forwardAmong dogs, short hair is dominant to long hair and dark coat color is dominant to white (albino) coat color. Assume that these two coat traits are caused by independently segregating gene pairs. For each of the crosses given below, write the most probable genotype (or genotypes if more than one answer is possible) for the parents. It is important that you select a realistic symbol set and define each symbol below. Assume that for cross (d), you were interested in determining whether fur color follows a 3:1 ratio. Set up (but do not complete the calculations) a Chi-square test for these data [fur color in cross (d)].arrow_forward
- The production of purple pigment in a certain species of flower is dependent upon two gene loci. You cross two purple flowered plants that are heterozygous at each gene locus. The offspring show the following phenotypes: 91 purple and 68 white.a. What is the simplified phenotypic ratio is observed in the offspring? What mode of inheritance is associated with this ratio? b. What is/are the genotype(s) of the purple offspring? What is/are the genotype(s) of the white offspring?arrow_forwardIn rats, hair color is either gray (G), black (g), or white. The white color is produced due to an epistatic recessive allele of gene "a". In other words, in order for the black or gray color to show up, the rat must have at least one dominant (A) epistatic allele. Two heterozygous Gray rats are crossed. Both rats are also heterozygous for the epistatic gene. Predict the probability that an offspring of this cross will: a. Express the gray phenotype b. Express the black phenotype c. Express the white phenotypearrow_forwardIn rats, hair color is either gray (G), black (g), or white. The white color is produced due to an epistatic recessive allele of gene "a". In other words, in order for the black or gray color to show up, the rat must have at least one dominant (A) epistatic allele. Two heterozygous Gray rats are crossed. Both rats are also heterozygous for the epistatic gene. Predict the probability that an offspring of this cross will: phenotype *Be sure to express each answer as a percentage! 12pt v a. Express the gray phenotype b. Express the black phenotype c. Express the white O English Paragraph BI U Αarrow_forward
- A number of true-breeding brown dogs were crossed with a true-breeding white breed. All the pups were brown. When several of the F1's were allowed to breed, the F2's were 92 brown, 58 black and 10 white. Provide a genetic explanation for these results and show the genotypes of the two original parents.arrow_forwardA researcher crosses mice with brown eyes and long tails, and the F1 progeny were recovered in the following numbers and phenotypic classes: F1: 6 apricot, short : 30 brown, long : 15 brown, short : 9 apricot, long You know the genes encoding these traits are autosomal, completely dominant and assort independently. You want to use a chi-square test to analyse these results. a) Making use of the appropriate genetic convention for naming alleles, give the genotype of the male parent in this cross. b) What is your null hypothesis for the chi-square test? c) Give the expected number of individuals in the "brown, long" class. d) You obtain a value of 3.47 for the chi-square test. What conclusion can you make from the results of the chi-square test? P df 0.995 0.975 0.9 0.5 0.1 0.05* 0.025 0.01 0.005 1 0.000 0.000 0.016 0.455 2.706 3.841 5.024 6.635 7.879 2 0.010 0.051 0.211 1.386 4.605 5.991 7.378 9.210 10.597 0.072 0.216 0.584 2.366 6.251 7.815 9.348 11.345 12.838 4 0.207 0.484 1.064 3.357…arrow_forwardIn roses, red petals (r) and waxy texture (wx) are encoded by two mutant alleles that are recessive to those that produce wild-type traits; yellow petals (r+) and soft texture (wx+). A rose homozygous for red petals and waxy texture is crossed to a rose homozygous for the wild-type traits. The F1 have yellow petals and soft texture. The F1 are crossed with roses that have red petals and waxy texture in a testcross. The progeny of this testcross are (1000 total): Yellow petals, soft texture 300 Yellow petals, waxy texture 126 Red petals, soft texture 110 Red petals, waxy texture 464 What is the genetic distance between red petals and waxy texture? a.57.4 b.76.4 c.23.6 d.30.9 e.42.6arrow_forward
- Human Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning