Question

The figure shows the cross-shaped chromosome pairing that forms during meiosis in a translocation heterozygote. The diagram shows two pairs of homologous chromosomes. Chromosome 1 is red and normally has genes A, B, C, D, E, and F. Chromosome 2 is blue and normally has genes P, Q, R, S, T, and U. The chromosomes labeled Mand N2 have the normal complement of genes in the correct order. The chromosomes labeled 71 and 72 have a reciprocal translocation. Complete the statements below using the correct words or phrases. Not all words and phrases are used. Chromosome pairing in a translocation heterozygote U T1 T S N2 S А в с D r a P a b C d RQP e E N1 T2 f F

Answer 1

1) If both the genes N1 and N2 are segregated and so are T1 and T2, there will production of complete and viable gametes. The gametes will be balanced because each gamete will have one copy of each gene.

2) These types of gametic pairs are called alternate pairs because of their orientation

3) When alternate segragation occurs like N1 with T2 and T1 with N2, then these types of pairs are called adjacent 1 pairs because they are placed adajacent to each other and 1 because they are the first type of combination.

4) But if N2 and T2 combines and N1 and T1 combines, then they are called adjacent 2 pairs because that rarely happens.

5) The gametes produced by such adjacent segregations are often unbalanced. This is because unlike the balanced case, here dissimilar gametes exists that are having two copies of same gene

6) The inviablity of the produced zygotes due to such unbalanced combinations and segregations is called semisterility (occurs mostly in reciprocal translocation and has 50% of the offsprings non viable or non sterile)