Passage:
In the late 1940s, geneticist Barbara McClintock investigated color mutation patterns in maize kernels, observing phenotypic variations that failed to conform to classical Mendelian inheritance ratios. Through meticulous cytogenetic analysis of chromosome 9, McClintock identified specific genetic elements that were capable of changing their physical positions within the genome. She designated these mobile elements as 'controlling elements'—now termed transposons—and demonstrated that their insertion into or excision from particular gene loci could suppress or reactivate surrounding gene expression. Contrary to the prevailing consensus of the era, which posited that chromosomes possessed fixed, immutable sequences of genes, McClintock proposed that genetic regulation was dynamic and modulated by spatial rearrangement. Although her initial presentations in 1951 were met with skepticism by the scientific community due to the entrenchment of the static genome paradigm, subsequent molecular discoveries in bacteria during the late 1960s confirmed the physical mechanism of transposition.
Consider each of the choices separately and select all that apply.
According to the passage, which of the following is explicitly stated regarding Barbara McClintock's research on maize?
- Her identification of controlling elements relied on cytogenetic examination of chromosome 9.Cevap
- BHer initial 1951 findings were immediately accepted as a clear refutation of classical Mendelian inheritance.
- The mobility of the genetic elements she identified could influence the activation state of nearby genes.Cevap