Which of the following statements about recombination is true? Recombinant frequencies higher than 25% are indications of no linkage. Recombinants of linked genes can be formed in the absence of crossover. Recombinants can be formed by crossovers during meiosis II Recombinant frequencies lower than 50% are diagnostic for linkage. Recombinants cannot be formed without crossovers during meiosis I
Added by Katherine F.
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Statement 1: Recombinant frequencies higher than 25% are indications of no linkage. This is true. If genes are unlinked, they assort independently, leading to recombination frequencies close to 50%. Statement 2: Recombinants of linked genes can be formed in Show more…
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Which of the following statement is TRUE? Recombinants cannot be formed without crossovers. Recombinants can only be formed for linked genes Recombinants can only be formed for alleles that follow independent assortment. Recombinants cannot be formed without crossovers between two linked genes. Recombinants of unlinked genes can only be formed by crossovers.
Sri K.
Why do calculated recombination frequencies between pairs of loci that are located relatively far apart underestimate the true genetic distances between loci? Recombination frequencies between widely separated genetic loci do not underestimate the true genetic distance. Double crossovers will be counted twice. Genetic recombination frequencies are an inaccurate method of determining genetic distances. The calculated recombination frequency underestimates the true crossover frequency because the double crossover progeny are not counted as recombinants. Because genetic maps are only accurate over short distances and therefore cannot be used for genes that are relatively far apart. Assume a mouse that is heterozygous for genes A and B (that is, Aa and Bb) is used in a test-cross mating: What percentage of each genotype would be expected among the offspring if these two linked genes are 20 map units apart and the heterozygote has the dominant alleles on one chromosome and the recessive alleles on the other? 40% of the offspring will exhibit A and B, 40% will exhibit A and b, 10% will exhibit a and B, and 10% will exhibit a and b. In an event where the centromere regions of two non-homologous acrocentric chromosomes become fused to form a single centromere, it is called a nonreciprocal translocation. Known Robertsonian translocation is responsible for an inheritable form of Turner syndrome. Recombination frequencies are similar for all genes, increase for genes on larger chromosomes compared to smaller chromosomes, and increase for more widely separated genes. They are different depending on whether the heterozygous genes are in the cis or trans configuration. Select this answer if all of the choices A-D are false. Hfr bacterial cells exhibit the highest levels of gene transfer because rather than existing as an isolated plasmid, the factor is incorporated within the main chromosome where it can transfer many chromosomal genes at one time. They do not require conjugation for gene transfer. Select this answer if none of the choices A-D are correct.
Katlin K.
Which of the following statements is not true regarding gene linkage? If a recombination frequency between two genes is greater than or equal to 50%, the genes are linked. Crossing over occurs during prophase I of meiosis The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. Linked genes are found on the same chromosome.
Nayan P.
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