The central dogma of molecular biology states that information flows in one direction from DNA to RNA to protein. However, exceptions exist, such as with viruses or laboratory interventions. The term “dogma” is not associated with religious beliefs. DNA replication, transcription, and translation are the three typical types of information flow. Reverse transcription, RNA replication, and direct translation of DNA into proteins are possible manipulations in the laboratory or with viruses. Backtracking from a protein to DNA or RNA or using proteins to build additional proteins is currently impossible.
The central dogma (sometimes capitalized as Central Dogma) of molecular biology is that information in biological systems flows in only one direction: from DNA to RNA to protein. The central dogma was first formulated by Francis Crick, one of the co-discoverers of the structure of DNA, in 1958 and popularized in a paper published in Nature in 1970. Since it was formulated, the central dogma has been found to central does not always keep (contrary to its name) and under some conditions, such as those involving viruses or special interventions in a laboratory, other types of information flow are possible.
The term “central dogma” is just a phrase; it does not mean that the idea is infallible or somehow associated with religious dogma. Crick later regretted using the word “dogma” to explain his idea of him, because of all the trouble it had caused him.
In biology, there are three typical types of information flow that occur in all living cells: DNA changes, DNA into RNA, and RNA into proteins. DNA is capable of self-replication in a process called DNA replication.
In the cell, RNA serves as a proxy, the signalman for protein-synthesizing DNA molecules. The process by which DNA creates RNA is called transcription. The complete readout of any organism’s DNA, called a genome, contains a complete set of instructions for making all of the RNA and proteins that make up the organism. Once RNA is created from DNA, it cannot be taken up or otherwise manipulated, and RNA cannot change RNA. Once RNA synthesizes proteins (called translation), the proteins cannot influence the information content of the DNA or RNA. However, DNA can make new proteins to take apart or otherwise manipulate pre-existing proteins.
In the laboratory or with viruses, three further manipulations are possible. One is DNA modifying RNA, called reverse transcription. This happens in the case of RNA retroviruses, such as HIV, which hijack the host cell’s DNA machinery. Another manipulation is the manipulation of RNA, called RNA replication, which occurs with some RNA viruses. The last is the direct translation of DNA into proteins, which has been demonstrated a few times in the laboratory, although it remains largely unexplored.
Several manipulations are impossible, at least with our current level of technology. These include backtracking from a protein to the DNA or RNA that made it, or using proteins to build additional proteins.
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