Dna Content Through Mitosis: And Meiosis Activity

Before any division occurs, a cell must replicate its DNA during the (Synthesis phase) of interphase. Consider a typical diploid human cell with a DNA content of 2C (representing two copies of each chromosome, one maternal and one paternal). During S phase, each chromosome is duplicated, producing two identical sister chromatids attached at a centromere. By the end of S phase and throughout the G2 phase , the DNA content has doubled to 4C . Crucially, though the quantity of DNA has doubled, the ploidy (number of chromosome sets) remains diploid (2n) because the sister chromatids are still considered part of a single chromosome.

No DNA replication occurs between Meiosis I and II. The cell starts Meiosis II with a 2C DNA content. In anaphase II, the sister chromatids finally separate. At the end of telophase II and cytokinesis, each of the four resulting gametes contains a 1C DNA content. The original 4C of DNA has been partitioned into four genetically unique cells, each with half the DNA of the original diploid parent. dna content through mitosis and meiosis activity

In prophase I, homologous chromosomes (one maternal, one paternal) pair up as bivalents. Crossing over occurs, swapping genetic material but not altering DNA quantity. In metaphase I, these homologous pairs align at the equator. During anaphase I, the homologous chromosomes are separated—not the sister chromatids. Consequently, each daughter cell receives one complete set of duplicated chromosomes. After telophase I and cytokinesis, each of the two cells has a DNA content of 2C (since each chromosome still consists of two sister chromatids), but the ploidy is now haploid (n) . Before any division occurs, a cell must replicate