The following points highlight the two main steps of mitosis. The steps are: 1. Karyokinesis 2. Cytokinesis. Step # 1. Karyokinesis: Karyokinesis (Gk. karyon- nucleus, kinesis- movement) is also called indirect nuclear division because the nucleus passes through a complicated sequence of events before forming two daughter nuclei. Though the process is continuous one without any pauses, it has been [...]
The following points highlight the four important phases of mitosis. The phases are: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase. Mitosis: Phase # 1. Prophase: During prophase, the individual chromosome appears in double threaded structure composed of two chromatids from the beginning. During this phase, the volume of the chromosomes too increases considerably and there is initiation of coiling [...]
A proteinaceous factor termed as maturation promoting factor (MPF), subsequently renamed as mitosis promoting factor, is identified and purified (Masui, Markert, Mailer). MPF is a heterodimer complex between kinase - a catalytic sub- unit and cyclin - a regulatory subunit (Fig. 5.27A). Kinase enzyme brings about phosphorylation of specific target proteins at different stages of the cell cycle which is [...]