Zoology. Mitosis and biglight phases of embryological development - Essay Example

Zoology Cells, such as those of skin, hair, and muscle, reproduce by means of mitosis. Mitosis is what happens with a eukaryotic cell is separated from the chromosomes within the cell nucleus and is divided into two identical sets of two daughter nuclei. These cells - the nuclei, cytoplasm, cell membrane, and organelles - are then further split, creating more groups of daughter cells. Mitosis is divided into these following phases: prophase, prometaphase, metaphase, anaphase and telophase. Prophase is when the chromatin liquefies into a structure known as a chromosome, which allows the chromatin to become visible.

Prometaphase is what happens when the nuclear envelope breaks itself into smaller fragments and then disappears entirely. Metaphase takes place when the chromosomes are situated in the center of the cell prior to splitting into the two daughter cell sets. Anaphase is when the chromosomes separate within the eukaryotic cell. The last phase, telophase, is when the stages and effects of prophase and prometaphase are reversed within the eukaryotic cell. Meiosis takes place when the chromosomes are split into halves, and is an essential part of sexual reproduction.

Meiosis has many more complex stages then mitosis, as seen in the following: meiosis 1, prophase 1 (which consists of these further stages: leptotene, zygotene, pachytene, diplotene, diakinesis, and synchronous processes), metaphase 1, anaphase 1, telophase 1, and meiosis II. In meiosis 1, the homologous chromosomes are separated into two haploid cells. During prophase 1, the pairs of homologous chromosomes recombine with other pairs. The following are the phases of prophase 1: leptotene - each separate chromosome condenses into long threads inside of the nucleus; zygotene - the thread-like chromosomes line up with each other; pachytene - the unrelated chromatids exchange small portions of genetic information; diplotene - the synaptonemal complex degrades and the homologous chromosomes sever from each other just a slight bit; diakinesis - the chromosomes liquefy even further during this stage; synchronous processes - two centrosomes, especially in the cells of animals, make their way to the two poles within the cell.

Metaphase 1 is when the homologous pairs move with each other. Anaphase 1 takes place when the recombination nodules are severed and detached from the kinetochore microtubules. Telophase 1 is when the chromosomes are entirely at the poles within the cell. Meiosis II is when four haploid cells are reproduced from the first two haploid cells. 2. The biglight phases of embryological development consists of cleavage, blastula, gastrula, and organogenesis. Cleavage is when the cells in the early embryo are divided.

Blastula is produced when the early embryo goes through the process of cleavage, as aforementioned, within the fertilized ovum. Gastrula is when the morphology of the early embryo is restructured and altered by cell migration, which is when the cells move to a particular location. After gastrula comes organogenesis, the stage during which the ectoderm, endoderm, and mesoderm are developed into the internal organs of the organism. Differentiation during embryological development is when a less specialized cell becomes even more specialized.

Specialization is when cells are specialized to complete certain functions and tasks within the cell and organism.