Friday, 18 May 2012


Re-discovering the discovered: Backtracking mechanism in E.coli cells, which play the role of Genomic Instability.


The genome is the complete ‘package’ of genes that an individual or its single cell contains (NSW Government, 2012). These packages of genes in our body are comprised of nucleic acids known as Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA); The two most significant and hereditarily  informative organic molecules of the human cell (NSW Government, 2012)(Grandy et al, 2012). DNA and RNA being responsible for many complex and intricate cellular processes, perform their roles by storing, representing, and duplicating the hereditary information of a nucleated cell (Grandy et al, 2012).
Through the two complex processes of transcription and translation, the DNA’s genetic material is passed to Messenger RNA (mRNA) and then to protein through these two major stages of synthesising protein (Reece et al, 2011). A recent study performed by researchers of the NYU School of medicine outlined a discovery of the mechanisms involved for the breakage of chromosomes in the cellular environment of bacteria such as Escherichia coli (NYU, 2012). The study provided an updated explanation to mutations that are produced by bacteria in order to manage and accustom to stressors like antibiotics (NYU, 2012).
Figure 1: Backtracking Mechanism of RNAP responsible for Genomic Instability within E.coli
Source: http://www.sciencedirect.com/science/article/pii/S0092867411008488
The study focused particularly on the collision of the three most contributing mechanisms in cellular movement: replisome (protein complex for DNA production in cell), RNA polymerase (particular enzyme for RNA production), and ribosome (molecular structure at which from protein is produced) (NYU, 2012). The researchers had conducted an experimental procedure of observing closely into living cells throughout various growth conditions, the co-directional and head-on collisions between the replisome and RNA polymerase (Both occur frequently in cells as both mechanisms share similar DNA path) (NYU, 2012). Results of the prolonged examination of the co-directional collisions displayed outcomes of DNA double strand breaks (DSB’s), or a change in the genetic material (NYU, 2012). Though, these results were drawn only when the replisome had collided with the backtracked RNA polymerase (backward sliding of RNA polymerase with DNA and RNA), a fundamental procedure from the transition of bacteria to humans. The research conducted had established that the maintenance of genomic stability is centralised by the support between translating ribosomes and RNA polymerase, as backtracking is prevented from occurring (NYU, 2012)(Dutta et al, 2011).
This discovery of the cellular processes involved in transitions from bacteria to humans is essential and a fundamental practice which will be valuable for every individual knowing how they came about and what makes them a human and not a microscopic bacterium like E.coli. Scientific discoveries to our evolutionary ladder could be unfolded to reveal more accurate and detailed information on the origin of many species and humans. This research should be continued for the benefit of the public’s knowledge and further development in unravelling our evolutionary stand.

REFERENCES:
JOURNAL ARTICLE:
1.      Dutta, D, Shatalin, K, Epshtein, V, Gottesman, M, Nudler, 19 August 2011. Linking RNA polymerase backtracking to Genome Instability in E. coli. Cell, Volume 146, Issue 4, 533-543,Accessed: 15 March 2012, http://www.cell.com/retrieve/pii/S0092867411008488
WEBSITE:
2.      Grandy, John K, 2012. "DNA." Encyclopedia of Time: Science, Philosophy, Theology, & Culture. Ed. SAGE Reference Online, Thousand Oaks, CA. Accessed: 16 Mar. 2012. http://sage-ereference.com.ezproxy.library.uq.edu.au/view/time/n156.xml?rskey=dXGnZ3&result=2&q=DNA#entrycitation

3.      New York University School of Medicine, 18 August 2011, New Mechanism of genomic instability revealed. Science daily, Accessed: 17 March 2012, from  http://www.sciencedaily.com/releases/2011/08/110818132227.htm

4.      NSW Government-Health: Centre for Genetics education, Feb 17, 2012, Glosaary of Genetic Terminology, Accessed: 18 March 2012, http://www.genetics.edu.au/information/glossary/
BOOK:
5.      Reece, B, Meyers, N, Urry, L, Cain, M, Wasserman, S, Minorsky, P, Jackson, R, Cooke, B, 2011, ‘From Gene to Protein’, in Sheppard, M, Campbell Biology, 9th Edition, Pearson Australia Group, China, pp. 334-335.

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