Concept explainers
Recall that Mendel obtained pure-breeding with either long or short stems and those hybrids had long stems (Fig. 2.8). Monohybrid crosses produced in F2 generation with a 3:1 ratio of long stems to short stems, indicating that this difference in stem length is governed by a single gene. The gene that likely controlled this trait in Mendel’s plants has been discovered, and it specifies an enzyme called G3βH, which catalyze the reaction shown in the accompanying figure. The product of the reaction, gibberellins, is a growth hormone that makes plants grows tall. What is the most likely hypothesis to explain the difference between the dominant allele (L) and recessive allele (l)?
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ND STONY BROOK UNIVERSITY LOOSELEAF GENETICS: FROM GENES TO GENOMES
- In the common daisy, genes A and B control flower color. Both genes have a dominant allele (A or B) and a recessive allele (a or b). At least one copy of each dominant allele is required for flowers to be colorful instead of white. (Explain and Justify your answers) 21.1) Predict the genotypes and phenotypes of the F1 progeny of a cross between two white-flowered plants, one homozygous AA and the other homozygous BB. A) AA bb, white B) aa BB, white C) Aa Bb, colorful D) Aa Bb, white E) aa bb, colorful 21.2) Predict the phenotypic ratio of the F2 progeny of a cross between two white-flowered plants, one homozygous AA and the other homozygous BB. A) 3 colorful : 1 white B) 9 colorful : 7 white C) 9 white : 7 colorful D) 15 white : 1 colorful E) 15 colorful : 1 white 21.3) The inheritance pattern of daisy flower color provides an example of what type of gene interaction? A) additivity…arrow_forwardE. W. Lindstrom crossed two corn plants with green seedlings and obtained the following progeny: 3583 green seedlings, 853 virescentwhite seedlings, and 260 yellow seedlings . Q. Explain how color is determined in these seedlings.arrow_forwardIn sweet peas, the given enzymatic pathway result to pigment formation in the flowers: A dihybrid plant is crossed to a white one which is heterozygous at the “C” locus (provided in the image). What is the genotype of the dihybrid plant? What is the genotype of the white plant? What kinds of flowers, colored or white, are to be expected from the cross above? Include the ratio.arrow_forward
- In sweet peas, the synthesis of purple anthocyanin pigment in the petals is controlled by two genes, B and D. What petal color would you expect in a pure breeding plant unable to catalyze the first reaction? Indicate the genotype and phenotype. 2. What petal color would you expect in a pure breeding plant unable to catalyze the second reaction? Indicate the genotype and phenotype. 3. If plants 1 and 2 are crossed, what petal color would the F1 plants have? Indicate the genotype and phenotype. 4. What ratio of purple : blue : white plants would you expect in the F2? Indicate the genotypes, phenotypes, and the F2 phenotypic ratio.arrow_forwardGiven the following pathway on the image: G and H are dominant alleles of the two independently assorting genes that produce an enzyme that catalyzes the conversion of one pigment to another, and g and h are recessive alleles that are non-functional. A true-breeding blue plant is crossed with a white plant of genotype ggHH. The F1s are allowed to self-mate. 1. What proportions would you expect in the F2 progeny? 2. Which is the epistatic allele?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_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_forwardPerform two consecutive crosses similar to those of Mendel for the following individual plants. Plants with round seeds (RR) are crossing with plants with wrinkled seeds (rr). After the first cross, cross the offspring together to generate F2 offspring. What are the genotypic and phenotypic ration of F2?arrow_forwardMendel obtained his initial pea plant varieties from local breeders who were developing new varieties that might be useful or interesting. To generate these new varieties, breeders formed hybrids between existing varieties of different phenotypic characteristics by cross-pollination, using techniques they doubtless taught to Mendel. After producing a hybrid, they allowed several generations of self-pollination, as happens naturally if the flowers are not disturbed. i. How many generations would it take for a breeder to have produced new pure-breeding varieties using this approach? ii. What is the probability that an individual in each of these generations (F2, F3, and F10) would be homozygous for one or the other allele of this gene? [Broad hint: if they’re not heterozygous, they’re homozygous!] please answer and explain properlyarrow_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_forwardGenes a and b are 20 cM apart. An a+ b+/a+ b+ individual was mated with an a b/a b individual.(a) Diagram the cross and show the gametes produced by each parent and the genotype of the F1.(b) What gametes can the F1 produce, and in what proportions?(c) If the F1 was crossed to a b/a b individuals, what off-spring would be expected, and in what proportions?(d) Is this an example of the coupling or repulsion link-age phase?(e) If the F1 were intercrossed, what offspring would be expected, and in what proportions?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage LearningBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStax