Meiosis StagesMeiosis occurs in eukaryotic organisms that reproduce sexually. This includes plants and animals. Meiosis is a two-part cell division process that produces sex cells with one half the number of chromosomes as the parent cell. There are two stages or phases of meiosis: meiosis I and meiosis II. At the end of the meiotic process, four daughter cells are produced.
Before a dividing cell enters meiosis, it undergoes a period of growth called interphase.
- G1 phase: The period prior to the synthesis of DNA. In this phase, the cell increases in mass in preparation for cell division. Note that the G in G1 represents gap and the 1 represents first, so the G1 phase is the first gap phase.
- S phase: The period during which DNA is synthesized. In most cells, there is a narrow window of time during which DNA is synthesized. Note that the S represents synthesis.
- G2 phase: The period after DNA synthesis has occurred but prior to the start of prophase. The cell synthesizes proteins and continues to increase in size. Note that the G in G2 represents gap and the 2 represents second, so the G2 phase is the second gap phase.
- In the latter part of interphase, the cell still has nucleoli present.
- The nucleus is bounded by a nuclear envelope and the cell's chromosomes have duplicated but are in the form of chromatin.
- In animal cells, two pair of centrioles formed from the replication of one pair are located outside of the nucleus.
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