Diploid nuclei of the ascomycete Neurospora crassa contain 14 chromosomes. A single diploid cell in an ascus will undergo one round of meiosis, followed in each of the daughter cells by one round of mitosis, producing a total of eight ascospores. If a single, diploid G2 nucleus in an ascus contains 400 nanograms (ng) of DNA, then a single ascospore nucleus of this species should contain how much DNA (ng), carried on how many chromosomes?

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Quizplus · Accepted Answer

In meiosis, the diploid number of chromosomes (2n) is halved to the haploid number (n). In this case, the diploid number is 14, so the haploid number is 7. Each round of mitosis produces two daughter cells, each with the same number of chromosomes as the parent cell. Therefore, after one round of meiosis and one round of mitosis, each ascospore nucleus will contain 7 chromosomes.The amount of DNA in a cell is proportional to the number of chromosomes. Therefore, if a single diploid G2 nucleus contains 400 ng of DNA, then a single ascospore nucleus will contain 400 ng / 2 = 200 ng of DNA.

Diploid Nuclei of the Ascomycete Neurospora Crassa Contain 14 Chromosomes