Activity 4
CELL DIVISION
by GEORGETTE E. ZALDIVAR
1. Distinguish between somatic and reproductive cell division and explain the importance of each.
Somatic cells are all body cells, excluding the gametes—sperm and ova. Somatic cell division is the type of cell division that occurs in somatic cells, which encompasses mitosis and cytokinesis. In this cycle, a somatic cell duplicates its contents and splits them into two. Each chromosome is duplicated before each mitotic division, resulting in a full set of chromosomes within the nucleus of each new cell after division. Hence, the daughter cells produced from this division are precisely similar to the parent cell. Somatic cell division is crucial for the growth and development of human bodies and for the embryonic development of living things. It also generates new cells and replaces injured, destroyed, or aging ones.
On the other hand, reproductive cell division, also called meiosis, is the reproduction process in which every new organism formed stems from the union of two different gametes—an ovum and a sperm—in a process called fertilization. Occurring in the gonads, the reproductive cell division produces gametes in which the number of chromosomes is only half of the initial number, contrary to mitosis. This phenomenon results in gametes containing a single set of 23 chromosomes called haploid cells. The diploid number of chromosomes can only be returned through fertilization. Thus, reproductive cell division is important as it allows for the sexual reproduction of diploid organisms. Moreover, it also contributes to genetic diversity by recombining genes, allowing the mixing of paternal and maternal genes; and aids in repairing genetic defects. Recombination that takes place during meiosis can also aid in the correction of genetic flaws in the progeny. Recombination can swap out a genetically defective allele on one parent's allele with the healthy allele on the other parent, resulting in healthy offspring.
2. What is the significance of interphase?
The stage of mitosis, known as interphase, is when a cell duplicates its DNA and makes more organelles and cytosolic components in preparation for cell division. It is a state of high metabolic activity, and it is during this stage that cell growth ensues. Interphase has three stages: the G1,S, and G2 stages.
Also known as the first gap phase, the G1 stage is where the cells cultivate and develop physically. Furthermore, this is where the cell replicates other organelles and creates the molecular building block necessary for later stages. The cell synthesizes a complete copy of the DNA in its nucleus in the S phase, or the synthesis phase. The cell also duplicates the centrosome, a microtubule-organizing structure that helps separate DNA during the M phase. The G2 phase, or the second gap phase, is where the cells further grow and produce proteins and organelles. The cell begins to reorganize its contents in preparation for mitosis. The end of this stage happens when mitosis starts, marking the end of the interphase.
The cell expands and engages in a variety of metabolic activities during the interphase, the time between cell division. The process of interphase is significant in cell division because it determines whether or not a cell should divide. It enables for cellular expansion, DNA replication, and the cell's last mitotic preparations.
REFERENCES:
BD Editors. (2012). Interphase. Retrieved from Biology Dictionary: https://biologydictionary.net/interphase/
The Albert Team. (2022). What is the Purpose of Meiosis? Retrieved from Albert: https://www.albert.io/blog/what-is-the-purpose-of-meiosis/
Tortora, G. J., & Derrickson, B. (2014). 3.7 Cell Division. In G. J. Tortora, & B. Derrickson, Principles of Anatomy and Physiology (pp. 91-95). John Wiley & Sons, Inc.
University of Leicester. (2020). The cell cycle, mitosis and meiosis for schools and colleges. Retrieved from University of Leicester: https://le.ac.uk/vgec/topics/cell-cycle/the-cell-cycle-schools-and-colleges