Briefly Describe The Main Biochemical Actions Of Telomerase And Discuss The Significance Of – Literature review Example
Function of Telomerase in Different Cells Function of Telomerase in Different Cells Introduction
This is a literature review paper that will discuss the function of telomerase enzyme and identify the biochemical activity of the enzyme. It will also focus on the functions of telomerase in different types of cells such as eggs, sperms, somatic cells and cancer cells. Chromosomes contain repeated DNA sequences at their ends called as telomeres. For the purpose of DNA replication in every cell division, these telomeres are shortened. Ultimately the chromosomes become frayed (Pardue & DeBaryshe, 2009). The problem is the replication of the daughter strand at the 5’ end. In certain specific cells like eggs, sperm and cancer cells the enzyme called telomerase performs the function of reconstruction of the telomeres and prolongs the cell life.
Figure 1A: Structure of telomere: Showing systemic representation of the telomeric DNA complex.
Figure 1B: Schematic representation oF shelterin complex combined with telomeric DNA. (Rubtsova, Vasilkova, Malyavko, Naraikina, Zvereva, & Dontsova, 2012)
Telomerase is a complex enzyme, which consists of a protein that acts as a reverse transcriptase and a piece of RNA that behave as a template. During the DNA replication process the CA (Cytosine, Adenine) rich end of the RNA template bases pair with GT (Guanine, Thiamine) rich single strand 3’ end of the DNA. The enzyme reverse transcriptase acts here by synthesizing DNA following the 5’→3’ sequence using the RNA template. After this step telomerase translocates to the new formed strand and the process of replication is repeated. After the GT rich strand gets the appropriate length, it is used by another enzyme primase as a template to synthesize the RNA primer that is extended to proper length by DNA polymerase and the primer is disconnected (Harvey & Ferrier, 2011, p. 408).
Figure 2: Action of Telomerase in base pairing at 5’ to 3’ end of the daughter strand. (Source: http://2014hs.igem.org/Team:TAS_Taipei/project/abstract)
Functions of Telomerase in different cells
The function of Telomerase enzyme is to maintain the length of the telomere. Each time a cell divides its length is reduce which is restructured by telomerase. The length of telomere shows the proliferative potential of cells that is how many times a cell can divide before it is dead (Papachristodoulou, Snape, Elliott, & Elliott, 2009, p. 361). In embryonic cells the telomerase is found in high amount which activates and maintains the length of the telomeres constantly therefore these cells have unlimited fission potential as the embryo keeps on developing rapidly till it becomes a fetus. In stem cells the activity of telomerase is slow which allows partial compensation for the shortening of the telomeres. In somatic cells telomerase is absent. The shortening of telomeres achieves the Hay flick limit, which is characterized as the state of senescence. Subsequently the cells attain the state of crisis and finally meet cell death. The cells, which survived the process, become tumor cells or cancer cells. In cancer cells the activity of telomerase is high. They can divide and multiply much rapidly and can maintain the length of telomeres by the help of telomerase (Rubtsova, Vasilkova, Malyavko, Naraikina, Zvereva, & Dontsova, 2012).
It was found that the function of telomerase is to aid in the replication process of DNA by preventing the cells from death and become abnormal. It keeps on maintaining the length of chromosomes until their death. The function of telomerase is distinguished in different types of cells that are normal and abnormal cells. In cancer patients inhibiting the telomerase activity can be used for the treatment of cancer.
Harvey, R., & Ferrier, D. (2011). Biochemistry (5th ed.). New York: Lippincott Williams & Wilkins.
Papachristodoulou, D., Snape, A., Elliott, W. H., & Elliott, D. C. (2009). Telomeres solve the problem of replicating the ends of eukaryotic chromosomes. In Biochemistry and Molecular Biology (5th ed.). Oxford: Oxford University Press.
Pardue, M.‐L., & DeBaryshe, G. (2009). Telomeres in Cell Function: Cancer and Ageing. John Wiley & Sons .
Rubtsova, M., Vasilkova, D., Malyavko, A., Naraikina, Y., Zvereva, M., & Dontsova, O. (2012). Telomere lengthening and other functions of telomerase. Acta Naturae , 4 (2), 44-61.