In this article we will discuss about the cell division in eukaryotes. Eukaryotic cell division involves two major events: (a) The division of nucleus into two daughter nuclei (karyokinesis), and (b) The division of cytoplasm to produce two daughter cells, each cell normally having a single daughter nucleus (cytokinesis). In eukaryotes there are two types of cell division, mitosis and [...]
In this article we will discuss about:- 1. Meaning of Meiosis 2. Stages of Meiosis 3. Duration 4. Significance. Meaning of Meiosis: Chromosome number remains constant between the generations in asexually reproducing organisms since reproduction in them is based on mitosis. But in most species sexual reproduction does take place; it involves fertilization, i.e. fusion of male and female gametes. [...]
The following points highlight the four main hypothesis proposed for the mechanism of crossing over. The hypothesis are: 1. The Classical and Neo-Classical Hypotheses 2. Partial Chiasma Type Theory 3. Belling's Hypothesis 4. Copy-Choice Hypothesis. Mechanism of Crossing Over: Hypothesis # 1. The Classical and Neo-Classical Hypotheses: The classical hypothesis of crossing over was proposed by Sax in 1932; it [...]