Genes and Cells
Cell production and division allows the human body to efficiently grow and maintain itself. To achieve this, the body must coordinate the interactions between thousands of production and division activities at any given time. This process is called cell proliferation.
Cell proliferation is highly regulated to maintain the supply, distribution and use of energy and chemicals, while maintaining chemical and temperature balance. Further, cell proliferation is not equal throughout the body. For instance, when it comes to the largest organ in the body, the skin, cells are automatically sloughed off and replaced with newer ones on a daily basis. In other parts, typically involving internal components like nerve cells and heart muscles, the body has significantly limited replacement and repair options.
Prior to division, the cell must first be perfectly duplicated based on the encoded genetic information contained within the DNA. This process, called DNA replication, is triggered by an enzyme called DNA polymerase. This enzyme facilitates the transcription of DNA molecules from deoxyribonucleotides by connecting the ends of the 3′ hydroxyl and the 5′ phosphate nucleotide groups. Each sequence of the DNA serves as a template for the nucleotides in a new sequence. Upon completion, a new identical DNA sequence will exists in the protein strand. If perfect replication is not achieved, the DNA polymerase will erase the sequence and construct a new one. This process will be repeated tens of thousands of times over on a daily basis.
After the replication is completed, the DNAs will coil unto themselves tightly to create chromosomes. Subsequently, each chromosome will split vertically, and thus, create two identical chromatids. Thereafter, each new pair of chromatids will be divided in the five phase mitosis – prophase, prometaphase, metaphase, anaphase and telophase.
Once mitosis is concluded, a further division occurs involving the cytoplasm. This process is called cytokinesis, which will ultimately lead to the formation of cell membranes and cell walls.
A systematic failure during division and proliferation will create cancer cells which will gradually coalesce into tumours.