Question

Name the stage of the cell cycle at which one of the following events occurs:

1. Chromosomes are moved to the spindle equator.
2. Centromere splits and chromatids separate.
3. Pairing between homologous chromosomes takes place.
4. Crossing over between homologous chromosomes takes place.

Answer 1

A. Chromosomes are moved to the spindle equator:

1. Metaphase is marked by the disintegration of nuclear envelope marks.
2. In this stage, chromosomes are made up of two chromatin sisters.
3. Chromosomes moved to the spindle equator and get aligned to the metaphase plate in the Metaphase stage.

B. Centromere splits and chromatids separate:

1. In Anaphase, the chromosomes that were aligned at the metaphase plate get split and form the future daughter chromosomes.
2. Thus, the process of splitting centromere and chromatin separately happens in Anaphase.

C. Pairing between homologous chromosomes:

1. Pairing between homologous chromosomes takes place in the sub-phase of prophase I called zygotene in meiosis.
2. During this phase the chromosomes start to pair together and this process is called synapsis.

D. Crossing over between homologous chromosomes:

1. Crossing over between homologous chromosomes takes place in pachytene, the third sub-phase of prophase I.
2. Crossing over is the process in which the exchange of genetic data takes place.
3. This process happens with the help of an enzyme called recombinase.