Central Dogma of Biology


The process of getting proteins from DNA, was first postulated by Francis Crick. However, Crick’s thoughts were more closely related to the transfer of biological ‘information’. In 1958, he had this to say:

The Central Dogma. This states that once ‘information’ has passed into protein it cannot get out again. In more detail, the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be possible, but transfer from protein to protein, or from protein to nucleic acid is impossible. Information means here the precise determination of sequence, either of bases in the nucleic acid or of amino acid residues in the protein.

 

Francis Crick c.1958

 


TL; DR

  • Francis Crick c. 1958 first postulated the Central Dogma.
  • The Central Dogma of Biology proposes that biological information can flow in one direction: from genetic material into protein.

 

Central Dogma of Biology: transfer of biological information.
Title: Central Dogma of Biology | Author: Genome Research Limited | Sourceyour genome  | License: CC BY 4.0

Claims of Francis Crick's Central Dogma

The Central Dogma states the following:

      1. Genetic information can be transferred to genetic information. Evidence of this has been seen in the following processes:
            • Replication; where information from a DNA molecule is copied into a new DNA molecule.
            • Transcription; where information from a DNA molecule is copied into a message RNA molecule.
            • Reverse transcription; where genetic information from an RNA molecule is copied into a DNA molecule. 

      1. Information can also transfer from genetic information to protein.
      2. Information cannot transferred from protein to genetic material. This proposition suggest the following:
            • → RNA cannot be created from protein.
            • → DNA cannot be created from protein.

Take a look at the slide show below for an analogy to the Central Dogma.

Retroviruses – like HIV, coronaviruses and Hepatitis – are an example in biology where RNA is transcribed into DNA.  These viruses store their genetic information in single stranded RNA molecules. Once they infect a host cell, reverse transcriptase is transcribed and the enzyme uses the viral RNA as a template by to synthesize DNA. The viral DNA is then incorporated into the host cell’s genome where it can be transcribed into mRNA and subsequently translated into protein.

 


 

There's more to the story...


While we covered several key scenarios that are predicted by the central dogma, it’s by no means a complete picture of the ways biological information can be transferred. For example:

        • → Some viruses are capable of RNA replication. 
        • → The direct translation of DNA into protein has been observed, albeit under artificial conditions in laboratories.
        • →  The field of epigenetics has shown that different ‘tags’ placed on genes can also confer information.

        •  

However, these cases are not necessarily in conflict with the central dogma.  Interesting and controversial scenarios arise at the protein level: one example being prions.  Prions are virulent, misfolded proteins that cause disease. When a prion interacts with a normal-folded protein (of the same amino acid sequence), the prion alters the tertiary structure of that protein to the conformation of the prion. If we consider this to transfer of structural information from protein to protein, some argue that prions violate the central dogma of biology. 

  1. yourgenome. “What is the ‘Central Dogma’?”. Cambridge, UK. Wellcome Genome Campus, https://www.yourgenome.org/facts/what-is-the-central-dogmaLicense: CC BY 4.0
  2. Fowler, S, Roush R, and Wise J. “Molecular Biology.” Concepts of Biology. Houston, TX: OpenStax, https://openstax.org/books/concepts-biology/pages/9-3-transcriptionLicense: CC BY 4.0 License TermsEdited & Adapted | Access for free at https://openstax.org/books/biology-2e/pages/1-introduction..
  3. Zedalis, J, and  Eggebrecht, J. “3.5 Nucleic Acids.” Biology for AP® Courses, p. OpenStax, https://openstax.org/books/biology-ap-courses/pages/15-1-the-genetic-codeLicense TermsEdited & Adapted | Access for free at https://openstax.org/books/biology-ap-courses/pages/1-introduction