The phenomenon of crossing over occurs during which of the following stages of meiosis?

✅Explanation:
Crossing over, a crucial step in genetic recombination, happens during the pachytene stage of prophase I in meiosis.
1.Leptotene: In this stage, chromosomes begin to condense but haven't paired yet. Crossing over cannot occur without pairing.
2. Zygotene: Homologous chromosomes pair up, forming synaptonemal complexes, but crossing over doesn't happen yet.

• 3. Pachytene: This is the key stage for crossing over. Homologous chromosomes are fully paired and tightly associated, allowing for:
-Double-strand breaks in corresponding positions on each chromosome.
-Exchange of genetic material between non-sister chromatids of the paired chromosomes.
-Formation of chiasmata, visible X-shaped structures marking the crossover points.
4. Diplotene: The synaptonemal complexes start to break down, and chiasmata become more visible. However, no new crossing over events occur at this stage.

🔴 Related Terminology:
-Meiosis: Cell division that produces gametes (sperm and egg) with half the number of chromosomes.
-Homologous chromosomes: Chromosomes with the same genes but potentially different alleles.
-Non-sister chromatids: Chromatids within a chromosome that are not copies of each other.
-Chiasma: X-shaped structure marking the point of crossing over between chromosomes.