There are two major steps in cell division. One is nuclear division and other is cytoplasmic division. Mitosis and meiosis are the two types of nuclear division. Following these processes, Anaphase is the stage in the process of cell division (mitosis or meiosis) in which daughter chromosomes move away from each other to the opposite sides of the cell. It is further classified into two as, anaphase 1 and anaphase 2. Anaphase 1 is that phase in which homologous chromosomes separate to each side of the cell, and the centromere is intact while in anaphase 2, the sister chromatids separate and the centromere splits into two which result in two separate chromatids. Another main difference in anaphase 1 and anaphase 2 is that anaphase 1 takes place in diploid cells while anaphase 2 takes place in haploid cells.
What is Anaphase 1?
Anaphase 1 is defined as the phase in which homologous (similar) chromosomes separate from each other and moves to opposite sides of the cell. During this phase, the cell starts to lengthen. In this phase, the chromosomes are arranged at the equator of spindles. Anaphase 1 occurs in a diploid cell. In anaphase 1, spindle fibers are attached to the centromeres of homologous chromosomes such that each centromere is attached to two spindle fibers. In anaphase 1, homologous chromosomes separate to opposite sides or poles of the nucleus, but the sister chromatids remain attached. One thing to be noticed that in anaphase one the centromere does not take place. Finally, each pole gets half number of chromosomes. In the end, one homologous chromosome will go to each daughter cell.
What is Anaphase 2?
Anaphase 2 is defined as the phase in which the sister chromatids separate, and the centromere splits into two which result in two separate chromatids. Anaphase 2 occurs in haploid cells. In this phase, the chromatids plates arrangement is rotated about 90 degrees about the arrangement in anaphase 1. In anaphase 2, the spindle fibers are attached to the same chromosome. Then the spindles pull the centromere resulting in the splitting of the centromere. Now the sister chromatids separate. Each chromatid reaches each pole, and at the end of the phase, each daughter cell has one sister chromatids. After anaphase 2, the cell is now ready to separate completely into daughter cells, finally resulting in four daughter cells at the end of the division.
Anaphase 1 vs. Anaphase 2
- Anaphase 1 occurs in a diploid cell and counter to this anaphase two occurs in the haploid cell.
- Anaphase 1 results in the separation of chromosomes, whereas anaphase 2 results in separation of two sister chromatids.
- In anaphase, one centromere remains intact whereas in anaphase two centromere splits.
- In anaphase one chromosomes separate to opposite pole and the sister chromatids are together, whereas in anaphase two chromosomes separate splitting the centromere and sister chromatids.