Mitosis + Meiosis

Mitosis

 Cells perform many different functions daily to maintain proper life functions such as cell division. This process is where a cell increases in size and then splits into two identical daughter cells. This occurs through a series of stages:

The cell cycle has the G1 phase, S phase, G2 phase, m phase, and finally cytokinesis.

The cell cycle. The cell cycle has the G1 phase, S phase, G2 phase, m phase, and finally cytokinesis.

• In the G1 phase, the cell is synthesizing DNA to prepare for cell division.

• Next, in the S phase, also known as synthesis, the DNA is duplicated so it could later be split into two cells equally.

• The phase after that is the G2 phase. This is where the cell further prepares for mitosis by replicating organelles and checks to make sure the cell is okay to continue with the splitting. If the cell has any defects, it usually performs apoptosis, which is where the cell self destructs.

• The M phase is where mitosis occurs, and following is cytokinesis. Mitosis is composed of many stages. In order, they are prophase, metaphase, anaphase, and telophase. 

  Interphase is the longest phase of the whole process since this includes the G1 phase, S phase, and G2 phase. This essentially prepares the cell for the division process itself. Prophase is the first stage of mitosis. This is where the DNA condenses into visible chromosomes and the nuclear membranes dissolves. This lets the chromosomes move freely in the cell. During prophase, the spindle fibers begin to form from the centrioles. Following this is metaphase where the chromosomes align in the middle of the cell to prepare for separation. The spindle fibers then attach to the chromosomes' centromeres. In anaphase, the chromatids are separated by the spindle fibers. They move to opposite ends of the cell. This means that the two resulting cells would get an identical set of chromosomes. Lastly, telophase is at the end of mitosis. The chromatids are at the opposite poles by this time and there are new nuclear membranes forming around each set of chromosomes. This would mean there are now 2 separate nuclei in the cell.

• To finish this off, there’s cytokinesis. Cytokinesis is where the cytoplasm is finally split, completing the formation of two daughter cells. This is the last step in cell division.

Cell division is essential in living organisms. You can find this taking place for growth, tissue repair, replacement of cells, etc. This is an important process that needs to be done properly. That is why biology has evolved for the mechanism to be perfect most of the time it is carried out. In multicellular organisms, there are specific checkpoints throughout the cycle, such as the G1 and G2, which allows the cell division to continue. This regulation helps cells that are either damaged or mutated, to stop itself from continuing to divide. The cell cycle overall is important to understand because this is a fundamental function of life and occurs throughout an organism's lifetime. 

Meiosis is the process in which cells divide to produce gametes, also known as sex cells.

Meiosis

Meiosis is the process in which cells divide to produce gametes, also known as sex cells. Meiosis has similar stages as mitosis in the sense that it has prophase, metaphase, anaphase, telophase, and cytokinesis. However, they are different in the sense that meiosis has each of these steps repeated once more. The phases go like this: Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis I, Prophase II, Metaphase II, Anaphase II, Telophase II, and Cytokinesis II. Meiosis is the same as mitosis for the most part. However, in metaphase, something called independent assortment happens. This is when the chromosomes randomly line up across the middle of the cell. Randomness will help determine genetic diversity. This principle of independent assortment essentially states that genes will separate independently while they develop. The rest of the phases carry out just like mitosis. Then, in the beginning of round 2 in meiosis, there should now be two daughter cells each with 23 chromosomes. Once again, the same steps repeat, resulting in four daughter cells. These daughter cells are haploid, meaning they contain just a half of the chromosomes the parent cells have. 

Combining gametes

After cells undergo meiosis, they are haploid. So, In order to make sure the cells contain a full set of chromosomes, they must go through fertilization. This is when two haploid cells combine to form diploid cells. During the process, the combination of genetic material from both parents helps ensure variation. Gametes are haploid. So, when two gametes combine, they form diploid zygotes. After the diploid zygotes are created, they undergo mitosis to help the organism develop.