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f. Assuming that all nuclear DNA is restricted to chromosomes and that the amoun

ID: 177495 • Letter: F

Question

f.   Assuming that all nuclear DNA is restricted to chromosomes and that the amount of nuclear DNA essentially doubles during the S phase of interphase, how much nuclear DNA would be present in each cell listed above? Note: Assume that the G1 nucleus of a mosquito cell contains 3.0 × 10-12 grams of DNA.
   g.   Given that the sex of Culex is determined by alleles of one gene, males heterozygous, Mm, and females homozygous, mm, illustrate a labeled chromosomal configuration (involving the symbols AmAp, BmBp, and CmCp and the M locus) in a primary spermatocyte at metaphase. Assume that the M locus is on the AmAp chromosome and that crossing over has not occurred between the M locus and the centromere.

Explanation / Answer

Answer f.

G1 nucleus of a mosquito cell contains 3.0 × 10-12 grams of DNA. So, the S phase will end up to give 6.0 × 10-12 grams of DNA; i.e. double the original amount.

After mitosis is complete each cell will contain 3.0 × 10-12 grams of DNA. After meiosis the amount of DNA will half and will become 1.5 × 10-12 grams of DNA.