The scientific impact of Tjio and Levan's findings stems from their work demonstrating __________ ?
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Answer: D. Gave the number of human chromosomes
Explanation
Tjio and Levan made a landmark contribution by accurately determining the exact chromosome number in human cells. Their scientific findings established that normal human somatic cells contain forty-six chromosomes. This discovery corrected long-standing scientific errors regarding human cytogenetics and paved the way for modern genetics. Joe Hin Tjio and Albert Levan published their revolutionary chromosomal counting research during the 1950s. Prior to their work, scientists incorrectly estimated that human cells possessed forty-eight chromosomes. Accurate staining and cell culture techniques enabled their precise microscopic observation of human chromosomes.
Knowing the correct human chromosome count is fundamental for diagnosing genetic disorders like Down syndrome. Medical cytogenetics relies heavily on accurate chromosomal mapping established by early pioneers in the field. Clinical laboratories routinely count chromosomes to identify structural abnormalities associated with various diseases. Barr bodies represent inactivated X chromosomes and were discovered by a different researcher named Murray Barr. Sex linkage patterns were primarily uncovered through early genetic breeding experiments conducted by Thomas Hunt Morgan. Mutational changes were investigated by various geneticists studying Drosophila rather than Tjio and Levan.
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