Question

If a diploid cell is 2N=8, draw the chromosomes of the following. How many chromosomes and chromatids would you see on the cells in the following stages.

a) Nullisomic for chromosome 2 in G1

b) Monosomic for chromosome 1 in G1

c) Tetrasomic for chromosome 4 in mitotic metaphase

d) Trisomic for chromosome 2 in G2

e) Triploid in metaphase 1 of meiosis

Answer 1

Nullisomic: when a pair of particular chromosomes is missing from the diploid cell then it is called nullisomic.

Monosomic: single chromosomes from the pair of a chromosome is missing than it is called monosomic.

Terasomic: when a particular chromosome present in double pair or in four copies then is called tetrasomy

Trisomic: A chromosome present in three copies then it is called trisomy.

Triploid: when there’s a presence of triple set of chromosomes in a cell is called triploid.

Now, According to the definition the genomic formula is

A) In a chromosome 2 shows nullisomic then total chromosomes are 2N-2 is 6 chromatids in G1

B) In this chromosome 1 shows monosomic then total chromosomes are 2N-1 I.e. 7 chromatids in G1

C) In this chromosome 4 shows tetrasomic then total chromosomes are 2N +2 I.e. 10 chromatids in mitotic metaphase

D) In this chromosome 2 shows trisomy then total chromosomes are 2N+1 I.e. 9 and 18 chromatids are present in G2 phase

E) In this total chromosomes are 2N+N I.e. 12 and 12 chromatids present in the metaphase 1