Central Dogma

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‘The Central Dogma’ of molecular biology is the term used to describe how the genetic information stored within DNA is first encoded into RNA and then used to produce functional proteins within the cell[1]. Although DNA contains all the genetic information needed to produce proteins, it uses RNA as an intermediary molecule to transfer the information, thus RNA molecules are often referred to as the ‘messenger’ molecules (mRNA), transferring the genetic information from DNA in order to produce proteins[2].

The central dogma was a theory first postulated by Francis Crick in 1970 and to this day, is still widely accepted. The basic idea for the hypothesis can be written as follows: Polynucleotides and polypeptides use RNA as an intermediate in their two-component system, or more simply: DNA ---> RNA ---> Protein[3]. The idea relies on the ability of the polynucleotides to encode proteins using their genetic information and the polypeptides' catalytic activity which includes enzymes able to synthesise DNA. Thus, the central dogma can be said to be based on the two processes: Transcription and Translation.

DNA contains very specific sequences of nucleotides which can act as a template for a strand of RNA to be produced through the process of transcription. The resulting strand of RNA then codes for a very specific sequence of amino acids. These can be joined together in the ribosome of the cell to produce a polypeptide chain in a process known as translation. Hence, all the information that is needed to make proteins initially comes from DNA molecules[4].

The two processes go hand in hand and furthermore, the whole central dogma theory is founded upon the irreversibility of the translation process. Crick hypothesised the theory after the discovery of reverse transcriptase as the discovery of such an enzyme made it clear that, without very complicated molecular machinery, it is impossible to go from a protein to nucleic acids[5].

However, wNucleic acidshilst this concept is true for the majority of our genes, recent studies have shown that not every gene found in DNA codes for a protein. In fact, some sequences of DNA can code for various types of RNA[6].

The Central Dogma is also essential to the RNA World Hypothesis.

References

  1. Becker, W., Hardin, J., Bertoni, G. and Kleinsmith, L.J. (2012) Becker’s World of the Cell. 8th Edition. San Francisco: Pearson Benjamin Cummins. (p. 645)
  2. Hartl, D.L. and Ruvolo, M. (2012) Genetics. 8th Edition. Burlington, MA: Jones and Bartlett Learning. (pp. 22-23).
  3. Crick F. The central dogma of molecular biology Nature Published 08/08/1970 Cited 05/12/2017 227(5258):561–563
  4. Hartl, D.L. and Ruvolo, M. (2012) Genetics. 8th Edition. Burlington, MA: Jones and Bartlett Learning. (pp. 22-23).
  5. Eugene V. Koonin Why the Central Dogma: on the nature of the great biological exclusion principle Published 16/09/2016 Cited 05/12/2017 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4573691/
  6. National Centre for Biotechnology Information (2007) Central Dogma of Biology: Classic View. Available at: http://www.ncbi.nlm.nih.gov/Class/MLACourse/Modules/MolBioReview/central_dogma.html (Accessed: 28/11/14)
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