Concept explainers
Cytoplasmic male sterility (CMS) in plants has been exploited to produce hybrid seeds (see Experimental Insight
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Genetic Analysis: An Integrated Approach (3rd Edition)
- In 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_forwardSome 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 F1 have purple flowers. When these F1 self-fertilize, the F2 appear in a ratio of 916 purple to 716 white. a. Give genotypes for the purple and white flowers in these crosses. b. Draw a hypothetical biochemical pathway to explain the production of purple and white flowers in sweet peasarrow_forwardn 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 sing 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 corn, male sterility is controlled by maternal cytoplasmic elements. This phenotype renders the male part of 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 following color-coded circles, simulate the crosses indicated below. Put the illustrations of crosses in the spaces provided. Be sure to include in the labels the genotypes and phenotypes of the offspring in each cross. Big light green circle - male-sterile cytoplasm Big orange circle - male-fertile cytoplasm Small orange circle - FF nucleus Small half-light green-half-orange circle - Ff nucleus Small light-green circle - ff nucleusarrow_forwardIn fruit flies, you are mapping three genes in a three point cross. The mutants are hairy body (h), sepia colored eyes (se) and female sterility (g). You cross a heterozygous parent with a homozygous recessive parent and obtain the following results: Type Number h se g. 5 + se + 450 + se g 27 ++g_ h se + + + + h + g. h + + TOTAL is the gene in the middle and the distance in map units between se and g is Oh; 16.4 se; 7.1 Oh; 7.1 70 82 7 327 32 1000 se; 16.4arrow_forwardConsider the first category of test-cross offspring shown in figure 8.2 (+b, LS). Consider also that the parents of the heterozygous female flies in the test cross had the following genotypes: bb, SS, and +, LL. A. What would be the physical phenotype of these flies? B. If PC was conducted with the DNA of one of these flies using the primers for the molecular marker, what would be the appearance of the bands on an electrophoresis gel with the PC products? C. If the gene for black body and the locus for the molecular marker (L long or S short) were unlinked, what proportion of the test-cross progeny would be black flies that are heterozygous for the molecular marker? What proportion would be flies with normal body color, which are homozygous for one form of the molecular marker? D. If the gene for black body and the locus for the molecular marker were linked, how would the proportion of flies be different?arrow_forward
- In com, male sterility is controlled by maternal cytoplasmic elements. However, the presence of a nuclear fertility restorer gene (F_) restores fertility to male sterile lines. a. What are the crosses male sterile female x FF male? Give the genotypes and phenotypes of the offspring in each cross. Explain.arrow_forwardIn tomato, the following genes are located on chromosome 2: + tall plant d dwarf plant + uniformly green leaves m mottled green leaves + smooth fruit p pubescent (hairy) fruit Results of the cross +++ / dmp and dmp / dmp were: + + + = 470 + m p = 1 + + p = 14 d + p = 25 d + + = 0 d m p = 441 + m + = 19 d m + = 30 Identify the single and double crossovers among the progeny.arrow_forwardRecall 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_forward
- Flower color in petunias is determined by the biochemical pathway shown below: A_ B_ C_ Yellow Orange > Green Blue aa bb Plants of genotype AAbbcc were mated to plants of genotype AaBbCc. Determine the phenotypic ratio expected from this cross and fill in the spaces in the ratio below with whole numbers in lowest form. lf none are expected in a class, then type the number 0 in the space. Yellow: Orange : Green: Bluearrow_forwardDraw a preliminary linkage map of the three loci. What is their order? (E.g. is the forked locus between yellow and cross-veinless, or outside this region?) As this is a preliminary linkage map - do not account for double crossovers. You should base the distances on this map off your map distances calculated: yellow and forked: 39.3 mu yellow and cross-veinless: 11.9 mu cross-veinless and forked: 33.6 muarrow_forwardIn a study, an undergraduate student discovered a new enzyme involved in the metabolism of serotonin. This enzyme is made up of 3 subunits of the same protein. To characterize this enzyme, the student used genetic approaches to induce mutations in the coding region of the gene that codes for this protein and performed crosses to measure the effects of genotypes on enzyme activity. A) Indicate directly in the diagram (via a bar graph) the predicted relationship between genotype and enzyme activity. (Al represents the wild-type allele, A2 represents the mutant allele). A2A2 A1A2 A1Α1 B) Explain the reasoning for your prediction. Enzyme Activityarrow_forward
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