Question

Which among the following is the correct sequence of prophase I of meiosis?

• A. Leptotene, pachytene, zygotene, diplotene, diakinesis
• B. Leptotene, diplotene, pachytene, zygotene, diakinesis
• C. Leptotene, zygotene, pachytene, diplotene, diakinesis
• D. Leptotene, zygotene, diakinesis, diplotene

Answer 1

The correct option is C Leptotene, zygotene, pachytene, diplotene, diakinesis

The correct sequence of prophase-I of meiosis is Leptotene, zygotene, pachytene, diplotene, diakinesis.
During prophase I, the chromosomes have already duplicated. During prophase I, they coil and become shorter and thicker and visible under the light microscope. The duplicated homologous chromosomes pair, and crossing-over occurs. Crossing-over is the process that can give rise to genetic recombination. At this point, each homologous chromosome pair is visible as a bivalent , a tight grouping of two chromosomes, each consisting of two sister chromatids. The sites of crossing-over are seen as crisscrossed nonsister chromatids and are called chiasmata. The nucleolus disappears during prophase I. In the cytoplasm, the meiotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. The nuclear envelope disappears at the end of prophase I, allowing the spindle to enter the nucleus.