The giraffe Giraffa camelopardalis has a diploid chromosome

The giraffe (Giraffa camelopardalis) has a diploid chromosome number of 60 and 2.85 pg of DNA occur in an ovum (egg). How many chromatids (total number) should be present at mitotic metaphase? How many tetrads (total number) are present in a metaphase I cell of meiosis? How many dyads (total number) are present in a meiotic metaphase II cell? How many monads (total number) are expected in the cells resulting from the completion of meiosis II? How many pictograms of DNA are present in: prophase II nucleus a GI nucleus of a liver cell a mitotic cell at G2 a meiotic cell at diplonema How many different kinds of gametes (assuming no crossing over) would be expected as a result of independent assortment of chromosomes during meiosis? How many different zygotic combinations of chromosomes would be expected as a result of random union of gametes? How many chromosomes would occur in: Primary spermatocyte at G2 Secondary ocyte at metaphase II Kidney cell at Gl

Solution

Dipodi chromosome 2n =60

In prohpas II there are n chromosomes so = 2.85/2=1.425 pg DNA will present

G1 nucleus of liver cell generally DNA do not get double so 2.85 pg

In mitotic cell atG2 phase has DNA doubles so, 2 x 2.85 =5.7pg.

The meiotic cell at diplonema or diplotene phase also has double amount of DNA =5.7 pg

There are 60 chromosomes so 2n =60 in which 29AA +XX in female and 29AA+XY in male

So there are two different types of gamete form in meiosis, 29A+X, 29A+Y

There are two types of zygotic combination will occur form 29A+X of female and 29A+X and 29A+Y of male.

29AA+XX and 29AA+XY

Primary spermatocyte at G2 has = 60x2 =120

Secondary oocyte = 60

Kidney cell at G1 has 60 chromosomes because of no division nature in kidney