Normal Diploid Somatic (Body) Cells of the Mosquito Culex Pipiens

question 13

Essay

Normal diploid somatic (body) cells of the mosquito Culex pipiens contain six chromosomes. Assign the symbols A^mA^p, B^mB^p, and C^mC^p to the three homologous chromosomal pairs. The "m" superscript indicates that the homolog is maternally derived; the "p" indicates a paternally derived homolog. Assume that in the genus Culex, the sex chromosomes are morphologically identical.
a) For each of the cell types given below, draw and label (with reference to the symbols defined above) an expected chromosomal configuration.
Mitotic metaphase
Metaphase of meiosis I
Metaphase of meiosis II
b) The stage at which "sister chromatids go to opposite poles" immediately follows which of the stages listed in (a)?
c) 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.
d) 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 A^mA^p, B^mB^p, and C^mC^p and the M locus) in a primary spermatocyte at metaphase. Assume that the M locus is on the A^mA^p chromosome and that crossing over has not occurred between the M locus and the centromere.

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Definitions:

Subjects Examined

The individuals or entities that are analyzed or tested in a study.

Obtained Value

The actual result or measurement found in a research study or experiment.

Significance Level

The significance level, often denoted as alpha (α), is the probability of rejecting the null hypothesis when it is actually true, serving as a threshold for determining the statistical significance of an effect.

Degrees of Freedom

The number of values in the final calculation of a statistic that are free to vary.