Concept explainers
In experiments published in
genetic linkage in corn (Zea mays) for genes controllingkernel color (colored is dominant to colorless) and starchcontent (starchy is dominant to waxy). Bregger performed two crosses. In Cross
In Cross
a. For each set of
b. Calculate the recombination frequency for each of theprogeny groups.
c. Are the results of these two experiments mutually compatible with the hypothesis of genetic linkage? Explainwhy or why not.
d. Merge the two sets of progeny data and determine thecombined recombination frequency.
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Genetic Analysis: An Integrated Approach (3rd Edition)
- Figure 8.10 In pea plants, purple flowers (P) are dominant to white (p), and yellow peas (Y) are dominant to green (y). What are the possible genotypes and phenotypes for a cross between PpYY and ppYy pea plants? How many squares would you need to complete a Punnett square analysis of this cross?arrow_forward. In a particular kind of ornamental flower, the wildtype flower color is deep purple, and the plants aretrue-breeding. In one true-breeding mutant stock, theflowers have a reduced pigmentation, resulting in alavender color. In a different true-breeding mutantstock, the flowers have no pigmentation and are thuswhite. When a lavender-flowered plant from the firstmutant stock was crossed to a white-flowered plantfrom the second mutant stock, all the F1 plants hadpurple flowers. The F1 plants were then allowed toself-fertilize to produce an F2 generation. The 277 F2plants were 157 purple : 71 white : 49 lavender. a. Explain how flower color is inherited. Is this traitcontrolled by the alleles of a single gene?b. What kinds of progeny would be produced if lavender F2 plants were allowed to self-fertilize?arrow_forwardThe distance between two molecular markers that are linked alongthe same chromosome can be determined by analyzing the outcomesof crosses. This can be done in humans by analyzing a family’spedigree. However, the accuracy of linkage mappingwith human pedigrees is fairly limited because the number of people in mostfamilies is relatively small. As an alternative, researchers can analyze a population of sperm, produced from a single male, and computelinkage distance in this manner. As an example, let’s suppose a maleis heterozygous for two polymorphic STSs. STS-1 exists in two sizes:234 bp and 198 bp. STS-2 also exists in two sizes: 423 bp and 322bp. A sample of sperm was collected from this man, and individualsperm were placed into 40 separate tubes. In other words, there wasone sperm in each tube. Believe it or not, PCR is sensitive enough toallow analysis of DNA in a single sperm! Into each of the 40 tubeswere added the primers that amplify STS-1 and STS-2, and then thesamples were…arrow_forward
- . A snapdragon plant that bred true for white petals wascrossed with a plant that bred true for purple petals, andall the F1 had white petals. The F1 was selfed. Among theF2, three phenotypes were observed in the followingnumbers:white 240solid purple 61spotted purple 19Total 320a. Propose an explanation for these results, showinggenotypes of all generations (make up and explain yoursymbols).b. A white F2 plant was crossed with a solid purple F2plant, and the progeny werewhite 50%solid purple 25%spotted purple 25%What were the genotypes of the F2 plants crossed?arrow_forwardWhen true-breeding mice with brown fur and short tails (BBtt)were crossed to true-breeding mice with white fur and long tails(bbTT), all of the F1 offspring had brown fur and long tails. TheF1 offspring were crossed to mice with white fur and short tails.What are the possible phenotypes of the F2 offspring? Which F2offspring are recombinant, and which are nonrecombinant? Whatare the ratios of phenotypes of the F2 offspring if independentassortment is taking place? How are the ratios affected by linkage?arrow_forwardNicotiana glutinosa (2n = 24) and N. tabacum (2n = 48) are two closely related plant species that can be intercrossed, but the F1 hybrid plants that result are usually sterile. In 1925, Roy Clausen and Thomas Goodspeed crossed N. glutinosa and N. tabacum, and obtained one fertile F1 plant (R. E. Clausen and T. H. Goodspeed. 1925. Genetics 10:278–284). They were able to self-pollinate the flowers of this plant to produce an F2 generation. Surprisingly, the F2 plants were fully fertile and produced viable seed. When Clausen and Goodspeed examined the chromosomes of the F2 plants, they observed 36 pairs of chromosomes in metaphase I and 36 individual chromosomes in metaphase II. Explain the origin of the F2 plants obtained by Clausen and Goodspeed and the numbers of chromosomes observedarrow_forward
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