please describe what happens to chromosones before mitosis..
The chromosomes go through four phases before mitosis.
1. Prophase- the chromosomes unravel
2. metaphase-the chromosomes line up at the equator or the metaphase plate.
3. anaphase-the chromosomes separate
4. telophase-the chromosomes move to oposite ends of the cell.
Before mitosis, the chromosomes undergo several changes in order to prepare for cell division. These changes occur during a phase called interphase, which consists of three main stages: G1, S, and G2.
During the G1 phase, the chromosomes are in a relaxed state called chromatin. Chromatin is composed of DNA molecules wrapped around proteins called histones. The chromatin is dispersed throughout the nucleus, and individual chromosomes cannot be easily distinguished.
In the S phase, DNA replication takes place. The DNA molecule unwinds, and each original strand serves as a template for the synthesis of a new complementary strand. As a result, each chromosome is duplicated, and two identical sister chromatids are formed. These chromatids are held together by a protein called the centromere.
During the G2 phase, the newly formed sister chromatids condense and become more visible as distinct structures within the nucleus. The chromosomes become more tightly coiled and take on a condensed, X-shaped appearance. This process is essential for the proper segregation of genetic material during mitosis.
Overall, before mitosis, the chromosomes transition from a relaxed chromatin state in the G1 phase to condensed and duplicated sister chromatids in the G2 phase. These changes ensure that each daughter cell receives a complete set of chromosomes during cell division.