Synapsis occurs during which phase?(a)Anaphase I(b)Telophase I(c)Prophase I(d)Cytokinesis

The correct answer is (c) Prophase I.
Synapsis is the process of pairing homologous chromosomes during meiosis. It occurs specifically during Prophase I of meiosis I, which is a critical phase for genetic recombination.
Events in Prophase I:
Prophase I is divided into five sub-stages:
1. Leptotene: Chromosomes begin to condense and become visible.
2. Zygotene:
o This is the stage where synapsis occurs.
o Homologous chromosomes pair up and align with each other, forming a structure called the synaptonemal complex.
3. Pachytene: Crossing over occurs, where genetic material is exchanged between homologous chromosomes.
4. Diplotene: The synaptonemal complex dissolves, and homologous chromosomes begin to separate, but remain connected at chiasmata (sites of crossing over).
5. Diakinesis: Chromosomes are fully condensed, and the nuclear membrane disintegrates, preparing for metaphase I.
Importance of Synapsis:
• Synapsis ensures that homologous chromosomes pair correctly, which is crucial for genetic recombination (crossing over).
• This leads to genetic variation in the offspring.
Why not the other options?
• (a) Anaphase I: This is the stage where homologous chromosomes separate and move to opposite poles. Synapsis does not occur here.
• (b) Telophase I: This is the stage where the nuclear membrane re-forms after chromosome separation. Synapsis does not take place.
• (d) Cytokinesis: Cytokinesis is the division of the cytoplasm following telophase. It is unrelated to synapsis.
Synapsis occurs during Prophase I of meiosis I, specifically in the zygotene sub-stage. Therefore, the correct answer is (c) Prophase I.