Central dogma of molecular biology

Information here means the precise determination of sequence, either of bases in the nucleic acid or of amino acid residues in the protein.He re-stated it in a Nature paper published in 1970: "The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information.

This is the simplistic DNA → RNA → protein pathway published by James Watson in the first edition of The Molecular Biology of the Gene (1965).

[7] While the dogma as originally stated by Crick remains valid today,[6][8] Watson's version does not.

Transcription is the process by which the information contained in a section of DNA is replicated in the form of a newly assembled piece of messenger RNA (mRNA).

Processing includes the addition of a 5' cap and a poly-A tail to the pre-mRNA chain, followed by splicing.

In prokaryotic cells, which have no nuclear compartment, the processes of transcription and translation may be linked together without clear separation.

Each tRNA bears the appropriate amino acid residue to add to the polypeptide chain being synthesised.

The nascent polypeptide chain released from the ribosome commonly requires additional processing before the final product emerges.

Some proteins then excise internal segments from their own peptide chains, splicing the free ends that border the gap; in such processes the inside "discarded" sections are called inteins.

Nonribosomal peptides often have cyclic and/or branched structures and can contain non-proteinogenic amino acids - both of these factors differentiate them from ribosome synthesized proteins.

On contact with the intein-free copy, the HEG domain initiates the DNA double-stranded break repair mechanism.

In turn it can convey information into new cells and reconfigure more functional molecules of that sequence into the alternate prion form.

Some scientists such as Alain E. Bussard and Eugene Koonin have argued that prion-mediated inheritance violates the central dogma of molecular biology.

[12][13] However, Rosalind Ridley in Molecular Pathology of the Prions (2001) has written that "The prion hypothesis is not heretical to the central dogma of molecular biology—that the information necessary to manufacture proteins is encoded in the nucleotide sequence of nucleic acid—because it does not claim that proteins replicate.

Many years later Jacques Monod pointed out to me that I did not appear to understand the correct use of the word dogma, which is a belief that cannot be doubted.

Similarly, Horace Freeland Judson records in The Eighth Day of Creation:[15] "My mind was, that a dogma was an idea for which there was no reasonable evidence.

This, before the discovery of the role or structure of DNA, does not predict the central dogma, but does anticipate its gene-centric view of life, albeit in non-molecular terms.