Question

In a heterozygous diploid cell in which gene B is on chromosome one, gene G is on chromosome two, and the cell contains alleles B ,b and G, g.

a. Draw and label the cell at Metaphase and Anaphase and at the end of Mitosis. Label each chromatid. Label the ploidy of each cell.

b. Draw and label the cells as to show the chromosomes lined up in the cell(s) at Metaphase of in Meiosis I and Meiosis II and the cells at the end of meiosis. Assume no crossing over occurs. Label each chromatid. Label the ploidy of each cell.

Answer 1

In a hetrozygous diploid cell there are 4 chromosomes. The ploidy of the cell is 2n=4 chromosomes. There are two homologous pair-

1(blue ink) contain the allele B

1(red ink) contain the allele b

2 (blue ink) contain the allele- G

2 (red ink) contain the allele.

The blue 1 is homolouge of red 1 and the blue 2 is homolouge of red 2

Now see the following figures-

a.1. Metaphase of the mitosis: There are 2n=4 chromosomes. Each chromosomes contain 2 chromatids (sister chromatids)

2. Anaphase: In anaphase of mitotic cell division, chromatids are separted and move to the opposite poles. each pole contain 2n=4 chromosomes (here one chromosome = one chromatid)

3. end of mitosis: at the end of mitosis 2 daughter cell produced each with 2n=4 chromosomes( diploid)

b.1 metaphase-I of meiosis: In this stage 2n=4 chromosomes are present (each with two sister chromatids). Chromosomes are arranged in equitorial position (homolougous pair are arranged side by side forming bivalents)

2. metaphase II: After anaphase 1 homologous chromosomes are separed and then metaphase II is occured. so in metaphase II each pole contain n=2 chromosomes (however the whole cell contain 2n=4 chromosomes).

End of meiosis: at the end of meiosis, 4 gametes will produce each with n=2.