A How many picograms if DNA are present in 1 A propane II nu

2. The giraffe (Giraffa camelopardalis) has a diploid chromosome number of 60 and 2.85 pg of DNA occur in an ovum (egg). (13 points; 1 points each) A. How many chromatids (total number) should be present at mitotic metaphase? A B. How many tetrads (total number) are present in a metaphase Icell of meiosis? C. How many dyads (total number) are present in a meiotic metaphase II cell? D. How many monads (total number) are expected in the cells resulting from the completion of meiosis ll? 3 o

Solution

A. Yes, the answer is correct asno. of no. of chromatids in mitotic metaphase is 2n (where, n = no. of chromosomes, i.e. 60) = 2 X 60 = 120.

B. Again, the answer is coorect. The Tetrad is equal to 2 homologous chromosomes (i.e. 4 chromatids) are paired and so appear as one structure in Metaphase of Meiosis I. Thus, if there are 60 chromosomes, after pairing the homologs together you will have 30 tetrads.

C. Again the answer is correct. Meiosis metaphase II is similar to mitosis except there will be half no of chromosomes. Thus total number of dyads is 30.

D. Correct. 30 monads are expected after meiosis. As each cell is haploid.