Which of the following events occurs during Meiosis I? The number of chromosomes increases from the haploid number to the diploid number. Non-sister chromatids are separated from each other. Sister chromatids are separated from each other. Homologous chromosomes are separated from each other.
The Correct Answer and Explanation is:
The correct answer is: Homologous chromosomes are separated from each other.
Explanation of Meiosis I
Meiosis is a specialized type of cell division that reduces the chromosome number by half, resulting in four haploid daughter cells from one diploid parent cell. This process consists of two consecutive divisions: Meiosis I and Meiosis II.
Meiosis I is often referred to as the reduction division because it reduces the number of chromosomes. It begins with a diploid cell (2n) that contains pairs of homologous chromosomes. The key events of Meiosis I include:
- Prophase I: During this stage, homologous chromosomes undergo synapsis, forming tetrads (groups of four chromatids). This is where genetic recombination, or crossing over, occurs, allowing for the exchange of genetic material between non-sister chromatids, enhancing genetic diversity.
- Metaphase I: The tetrads line up along the metaphase plate. Spindle fibers attach to the centromeres of the homologous chromosomes.
- Anaphase I: This is where homologous chromosomes are separated from each other and pulled toward opposite poles of the cell. It is crucial to note that, unlike mitosis, the sister chromatids remain attached at this point.
- Telophase I: The cell undergoes cytokinesis, resulting in two haploid cells (n), each containing one chromosome from each homologous pair.
It’s important to clarify the incorrect options:
- The number of chromosomes does not increase during Meiosis I; rather, it decreases from diploid to haploid.
- Non-sister chromatids are not separated; they remain together during Anaphase I.
- Sister chromatids are not separated until Meiosis II, where they are eventually pulled apart during Anaphase II.
In summary, the significant event of Meiosis I is the separation of homologous chromosomes, resulting in a reduction in chromosome number, crucial for sexual reproduction and genetic variation.