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 G 2 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?

The question is incomplete as it does not have the option which are:

A) 100, 7

B) 100, 14

C) 200, 7

D) 200, 14

E) 400, 14

A) 100, 7

Explanation:

The ascomycetes reproduce by the forming ascospores which are formed by the process of meiosis thus from 1 Parent cell, 4 daughter cells are reproduced. The 4 ascospores then undergo the mitosis and 4 daughter ascospores form 8 ascospores.

If the parent cell of an ascospore contains  

1. Ploidy- 2n=14 chromosomes, therefore, Meiosis process will reduce the number to half and will form the n=7 in daughter cells.

2. The DNA amount- in G2 stage will be 400 ng therefore during meiosis I, two cells with 200 ng DNA and then two more cells with 100 ng will be formed after meiosis II.

Thus, A) 100, 7  is correct.

in situ hybridization has been widely used for research applications, including clinical cytogenetics, gene mapping, tumor biology and studies of chromosome evolution.