Two genes interact to produce various phenotypic ratios among
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Chapter 4 Solutions
Genetic Analysis: An Integrated Approach Plus Mastering Genetics with Pearson eText -- Access Card Package (3rd Edition) (What's New in Genetics)
- Some sweet-pea plants have purple flowers and others have white flowers. A homozygous variety of sweet pea that has purple flowers is crossed with a homozygous variety that has white flowers. All the F1have purple flowers. When these F1 self-fertilize, the F2 appear in a ratio of 916 purple to 716 white. a.Draw a hypothetical biochemical pathway to explain the production of purple and white flowers in sweet peas.arrow_forwardExplain at the biochemical or enzymatic level, the phenotypic consequencesof alleles incase of following cross. Rr (pink flower) x Rr (pink flower) (progeny are 1 RR (red flower) :2 Rr (pink flower): 1rr(white flower) how alleles contribute to a phenotype through metabolism.arrow_forwardIn the fungus Neurospora, a strain that is auxotrophic for thiamine (mutant allele t) was crossed with a strain that isauxotrophic for methionine (mutant allele m). Linear asci were isolated and classified into the following groups: a. Determine the linkage relations of these two genes to their centromere(s) and to each other. Specify distances in map units. b. Draw a diagram to show the origin of the ascus type with only one single representative (second from right).arrow_forward
- Recall that red color (R) in four-o’clock flowers is incompletely dominant over white (R ′). In the following crosses, give the genotypes of the gametes produced by each parent and the flower color of the offspring: R/R ′×R/R ′; R′/R ′×R/R ′; R/R×R/R ′; R/R×R′/R ′arrow_forwardIn rice, male sterility is controlled by maternal cytoplasmic elements. This phenotype renders the male part of rice plants (i.e. the stamen) unable to produce fertile pollen; the female parts, however, remain receptive to pollination by pollen from male fertile rice plants. However, the presence of a nuclear fertility restorer gene F restores fertility to male-sterile lines. Give the result(s) of the cross and explain the phenotype of the offspring.arrow_forwardIn corn, male sterility is controlled by maternal cytoplasmic elements. This phenotype renders the male part of the corn plants (i.e the tassel) unable to produce fertile pollen; the female parts, however, remain receptive to pollination by pollen from male fertile corn plants. However, the presence of a nuclear fertility restorer gene F restores fertility to male sterile lines Using the cardboard chips, simulate the crosses indicated below. Give the genotypes and phenotypes of the offsprings in each cross, and properly label the nucleus and the cytoplasm of each individual in the cross Legend male sterile cytoplasm Male fertile cytoplasm FF nucleus Ff nucleus ff nucleus A. Male sterile female x FF male Explain the phenotype of the offspring B. Male sterile female x Ff male Explain the phenotype of the offspringarrow_forward
- In c. elegans, genetics model organism, movement problems (unc) and small body size (sma) are encoded by two mutant alleles that are recessive to those that produce wild-type traits (unc+ and sma+). A worm homozygous for movement problems and small body is crossed with a worm homozygous for the wild-type traits. The F1 have normal movement and normal body size. The F1 are then crossed with worms that have movement problems and small body size in a testcross. The progeny of this testcross is: Normal movement, normal body size 210 Movement problems, normal body size 9 Normal movement, small body size 11 Movement problems, small body size 193 a)From the test cross results, can you tell if the two genes are on the same chromosome or not? Explain your reasoning. b)What phenotypic proportions would be expected if the genes for round eyes and white body were located on different chromosomes? (please explain hot to get to these conclusions)arrow_forwardIn the model plant Arabidopsis thaliana, the following alleles were used in a cross: T = presence of trichomes t = absence of trichomes D = tall plants d = dwarf plants W = waxy cuticle w = nonwaxy A = presence of purple anthocyanin pigment a = absence (white) The T/t and D/d loci are linked 26 m.u. apart on chromosome 1, whereas the W/w and A/a loci are linked 8 m.u. apart on chromosome 2. A pure-breeding double-homozygous recessive trichomeless nonwaxy plant is crossed with another pure-breeding double-homozygous recessive dwarf white plant. a. What will be the appearance of the F1? b. Sketch the chromosomes 1 and 2 of the parents and the F1, showing the arrangement of the alleles.c. If the F1 is testcrossed, what proportion of the progeny will have all four recessive phenotypes?arrow_forwardIn a wild-type fungus, protein E (encoded by the haplosufficient gene E) normally dimerizes to catalyzes a biochemical reaction necessary for the production of a dark pigment. Ed represents a mutant, dominant negative allele of gene E. What is the predicted phenotype of a fungus cell of genotype E*/Ed, and why? O wild type (normal production of the dark pigment), as E is haplosufficient mutant (no pigment production), as no dimers will form in the heterozygous mutant (no pigment production), as the mutant allele Eg is dominant O wild type (normal production of the dark pigment), as dimers of wild-type and mutant protein E will be formed in the heterozygousarrow_forward
- Consider 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 corn snakes, the wild-type color is brown. Oneautosomal recessive mutation causes the snake to beorange, and another causes the snake to be black. Anorange snake was crossed to a black one, and the F1offspring were all brown. Assume that all relevantgenes are unlinked.a. Indicate what phenotypes and ratios you wouldexpect in the F2 generation of this cross if there isone pigment pathway, with orange and black beingdifferent intermediates on the way to brown.b. Indicate what phenotypes and ratios you wouldexpect in the F2 generation if orange pigment is aproduct of one pathway, black pigment is the product of another pathway, and brown is the effect ofmixing the two pigments in the skin of the snakearrow_forwardAn ebony strain of flies was discovered to be sensitive to carbon dioxide. Crossing a female sensitive strain with male resistant strain gave all sensitive offspring. The offspring of an F1 female crossed with a resistant male were all sensitive. Using the following key to your illustrations using shapes, make a reciprocal cross up to the F2 generation. Put your illustrations in the space provided below. Label the phenotypes of all individuals in the reciprocal cross. Adjust spacing, if necessary. Make sure that the complete cross(es) can fit the same page. Big blue circle - male cytoplasm Big pink circle - female cytoplasm Small half-blue-half-pink circle - F1 nucleus Small blue circle - male nucleus Small pink circle - female nucleusarrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning