Prophase I of meiosis comprises 5 stages, each defined by specific events:
• Leptotene: Chromosomes condense and become visible microscopically.
• Zygotene: Homologous chromosomes pair, forming a synaptonemal complex.
• Pachytene: Homologous chromosomes undergo crossing over.
• Diplotene: The synaptonemal complex disassembles, and chiasmata (crossover points) become visible.
• Diakinesis: Chromosomes condense further, and chiasmata move to terminal positions, preparing for separation.
The sequential order is Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.
| List-I | List-II |
|---|---|
| (A) Alkaline phosphatase | (i) Removes phosphate group at 5’ end of DNA |
| (B) DNA Polymerase | (ii) Nick translation |
| (C) SI Nuclease | (iii) Cleaves ssDNA |
| (D) DNase I | (iv) Cleaves DNA |
| List-I | List-II |
|---|---|
| (A) IgA | (i) Basophils |
| (B) IgE | (ii) Secretory components |
| (C) IgG | (iii) Pentamer |
| (D) IgM | (iv) Crosses Placenta |