CELLULAR DIVISION AND REPLICATION WITHIN MITOSIS AND MEIOSIS
The processes of mitosis and meiosis were examined along with their frequency as well as each of the different steps and their time duration. It was found that the interphase stage of both mitosis and meiosis was the longest of all the stages as this was where most of the ‘action’ was happening such as cell growth and duplication of all cell organelles and chromosome replication also. It was also found that mitosis and meiosis have similar stages, however, they also have a lot of differences such as the end result and what is happening throughout each stage.
The two processes of cellular division are mitosis and meiosis. The normal process of cellular division is mitosis where two daughter nuclei are produced and have equivalent genetics to the parent nucleus. However, meiosis is the variation of cellular division where gametes are produced and each daughter cell yields half the DNA from the parent cell. Also, before mitosis and meiosis can occur chromosomes must replicate in order to produce identical chromatids and they are each connected to a centromere. As pointed out before, mitosis is the process of cell division and the end result of this is duplicated chromosomes with two daughter nuclei that are both identical to the parent nucleus. Mitosis can be used for growth, repairing, and asexual reproduction for an organism. There are five main steps in the mitosis cycle and they are interphase, metaphase, anaphase and telophase.
Firstly, interphase has a lot going on and starts off by the cell increasing in size and mass and duplication of the cell organelles, such as the ribosomes, mitochondria, endoplasmic reticulum and centrioles. The DNA is then synthesized along with chromosomal duplicates being produced. At the centromere the chromosomes are then joined together, called sister chromatids. Next is prophase and the chromosomes become dense and visible as they were not in interphase. The nuclear membrane and the nucleolus then start to disappear and a spindle starts to form which is a set of microtubular fibres. In an animal cell, however, the centriole pairs move towards the top or the bottom of the spindle.
Metaphase is the third step of the mitosis cycle and this is where the chromosomes align themselves along the metaphase plate which is perpendicular to the centre of the spindle.
Following this, anaphase occurs. During anaphase the sister chromatids split apart at the centromere and travel towards opposite ends of the spindle and each individual chromatid is now considered a full chromosome.
Lastly is telophase and this is where the chromosomes reach the ends of the spindle and then it starts to break down. New nuclear membranes are then formed around the chromosomes and they start to unfold.
Cytokinesis then starts to begin as a cleavage furrow in animal cells, however, in a plant cell it is called a cell plate.
Meiosis, as mentioned earlier, is the process where nuclear division does occur, however, it is through sexual reproduction. Gametes are produced and only receive one set of a chromosome pair, therefore, half of what the parent cell carries. There are two phases of meiosis, Meiosis I and Meiosis II.
Before the first phase, meiosis I begins, where cell organelles and chromosomes are all duplicated and the DNA is synthesized. The chromosomes along with their duplicates are joined at the centromere region. All together this is considered to be one chromosome but with two parts called sister chromatids. The chromosomes become visible once they become condensed during prophase I. Prophase I is where the exchange of genetic material between homologous chromosomes occur, as well as chromosome condensing and the nucleolus and nuclear membrane disappear. A spindle then starts to form and a synapsis process occurs where the homologues align.
Metaphase I follows the prophase step and...