Concept explainers
(a)
To describe: The conclusion which is obtained from the nondisjunction and recombination frequencies and the way by which trisomic frequencies are influenced by the recombination frequencies
Introduction: The chromosomes are small structures which carry genes. These chromosomes transfer from one generation to another and show the similarity in the progeny. There are 23 pairs of chromosomes found in a cell.
(b)
To describe: The selective advantage of positive chromosomal interference
Introduction: The chromosomes carry genetic information of an organism. These are thread-like structures which are found in the nucleus of the cell. The traits of an organism are carried by the chromosomes from one generation to another.
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Concepts of Genetics (12th Edition)
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- A scientist working with Drosophila flies studies wing length, an X-linked characteristic. He has pure-breeding lines of short-winged and long-winged flies available. He decides to use reciprocal crosses for his work.i) What are reciprocal crosses? ii) Provide an example of the reciprocal crosses this scientist will do.iii) If the gene for wing length was sex-linked, but present in the pseudoautosomal region, what would you expect the outcome of a reciprocal cross to be with regards to males and females?arrow_forwardSelect the statements below that are TRUE. Select 4 correct answer(s) Question 14 options: A) Mutations are induced to occur in response to a selective pressure. B) Crossover suppression occurs when no recombinant progeny are observed between two genes located within a homozygous paracentric inversion. C) The ends of each chromosome are replicated by an RNA-protein complex called telomerase. D) When a mismatched base pair occurs during DNA replication, mismatch repair corrects the mismatch by replacing the nucleotide on the template strand. E) Mutations occur spontaneously and so may be pre-existing in a population when a selective pressure arises. F) When two genes are linked, the frequency of recombinant types exceeds the frequency of parental types. G) The choice…arrow_forwardThe mutations called bobbed in Drosophila result from variable reductions (deletions) in the number of amplified genes coding for rRNA. Researchers trying to maintain bobbed stocks have often documented their tendency to revert to wild type in successive generations. Propose a mechanism based on meiotic recombination which could account for this reversion phenomenon. Why would wild-type flies become more prevalent in Drosophila cultures?arrow_forward
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- In 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_forwardUsing figure 1 and the following background information answer the following questions. Identification of the genetic cause of hornlessness in cattle has been the subject of intensive genetic and genomic research, culminating in the nomination of two different candidate neomutations on cattle chromosome 1 that are predicted to have arisen 500-1,000 years ago: a complex allele of Friesian origin (PF), an 80,128 base pair (bp) duplication (1909352–1989480 bp), and a second, simple allele of Celtic origin (PC) corresponding to a duplication of 212 bp (chromosome 1 positions 1705834–1706045) in place of a 10-bp deletion (1706051–1706060)We report the use of genome editing using transcription activator-like effector nucleases (TALENs) to introgress the putative PC POLLED allele into the genome of bovine embryo fibroblasts to try and produce a genotype identical to what is achievable using natural mating, but without the attendant genetic drag and admixture. In our previous studies, we…arrow_forwardBased on the data in Table 1, which individual(s) is/are heterozygous? Select all that apply a) B IV-8 b) C IV-3 c) B IV-9 d) A IV-3arrow_forward
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