Question

The chiasmata are formed as a result of

• A. Exchange of parts of paired homologus chromosome.
• B. Exchange of part of unpaired non-homologus chromosome.
• C. Duplication of parts of paired homologus o chromosome.
• D. Loss of parts of unpaired non-homologus chromosome.

Answer 1

The correct option is A Exchange of parts of paired homologus chromosome.

The chromosomal crossover is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs during prophase I of meiosis during a process called synapsis. Synapsis begins before the synaptonemal complex develops, and is not completed until near the end of prophase I. Crossover usually occurs when matching regions on matching chromosomes break and then reconnect to the other chromosome. This process begins in early stage of prophase I which is called leptotene.