A diploid cell contains three pairs of homologous chromosomes designated C1 and C2, M1 and M2, and S1 and S2. No crossing over occurs. What combinations of chromosomes are possible in (a) daughter cells following mitosis? (b) cells undergoing the first meiotic metaphase? (c) haploid cells following both divisions of meiosis? a) There is only one combination of chromosomes in the daughter cells following mitosis because they (the daughter cells) contain all the homologous chromosomes of the original 'mother' cell.
b) There will be 8 combinations of chromosomes in the first meiotic metaphase b/c the three tetrads that result from pairing of homologous chromosomes of non-sister chromatid pairs align at the metaphase plate at random and this creates two possible orientations for each tetrad or a total of 2n combination (where n equals the haploid number of chromosomes). In this case 23 = 8 possible combinations.
c) There will be 8 different combinations of haploid chromosomes in the haploid cells (gametes). The reason is because each of the eight possible tetrad arrangements present in prophase I give rise to one of the possible arrangements of monads in the final mature gamete. The list is as follows:
i. C1, M1, S1
ii. C1, M1, S2
iii. C1, M2, S1
iv. C1, M2, S2
v. C2, M1, S1
vi. C2, M1, S2
vii. C2, M2, S1
viii. C2, M2, S2
***NOTE - There were 8 tetrads in the primary oocyte or primary spermatocyte, which would generate 2 pairs of 8 dyads in the secondary oocyte or secondary spermatocyte and then there would be 8 monads in the ootids or spermatids as well as in their developmental products the ova (plural of ovum) and the spermatozoa (sperm cells).