An animal heterozygous for a reciprocal balanced translocation has the following chromosomes:
           MN • OPQRST
           MN • OPQRjkl
           cdef • ghijkl
           cdef • ghiST

Diagram the pairing of these chromosomes in prophase I.

Key Concepts

Heterozygous Reciprocal Balanced Translocation

A heterozygous reciprocal balanced translocation occurs when two non-homologous chromosomes exchange segments, resulting in a rearrangement of genetic material. In this case, one chromosome carries one arrangement of genes, while its homologous partner carries a different arrangement. This can affect gene expression and segregation during meiosis, but if balanced, it typically does not lead to a loss of genetic material.

Prophase I of Meiosis

Prophase I is the first stage of meiosis, where homologous chromosomes pair up and exchange genetic material through a process called crossing over. This stage is crucial for genetic diversity, as it allows for the recombination of alleles. The pairing of chromosomes, known as synapsis, forms structures called tetrads, which consist of four chromatids, facilitating the exchange of segments between homologous chromosomes.

Chromosome Pairing and Diagramming

Diagramming chromosome pairing involves visually representing how chromosomes align during prophase I. In the case of a heterozygous reciprocal balanced translocation, the diagram must show the unique arrangements of the involved chromosomes, indicating how they pair and where crossing over may occur. This visual representation helps in understanding the genetic implications of the translocation and the potential outcomes for gametes.