Meiosis I
Meiosis I
Meiosis I (/maɪˈoʊsɪs/ my-OH-sis) is the first phase of meiosis, a type of cell division that reduces the number of chromosomes in a cell by half. This process is crucial for sexual reproduction and leads to the formation of gametes or sex cells.
Etymology
The term "meiosis" comes from the Greek word "meiōsis," meaning "to make smaller." This is in reference to the reduction of chromosome number that occurs during this process.
Process
Meiosis I begins with Interphase, during which the DNA in the cell is replicated. This is followed by four main stages: Prophase I, Metaphase I, Anaphase I, and Telophase I.
In Prophase I, the chromosomes condense and pair up, forming homologous chromosomes. The paired chromosomes exchange genetic material in a process known as crossing over.
During Metaphase I, the paired chromosomes align at the cell's equator. This is followed by Anaphase I, where the homologous chromosomes separate and move towards opposite poles of the cell.
Finally, in Telophase I, the cell divides into two, each with a unique set of chromosomes. This is followed by Cytokinesis, which divides the cytoplasm and completes the formation of two daughter cells.
Significance
Meiosis I is significant as it ensures genetic diversity in offspring. The crossing over of genetic material during Prophase I leads to new combinations of genes, which contributes to genetic variation.
Related Terms
- Meiosis II: The second phase of meiosis, which further divides the daughter cells from Meiosis I, resulting in four haploid cells.
- Mitosis: A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.
External links
- Medical encyclopedia article on Meiosis I
- Wikipedia's article - Meiosis I
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