What are you going to learn?
- What is the central dogma of molecular biology?
- How does the genetic information flow in the organism?
- How has the theory changed since it was first formulated?
- terms: reverse transcription, RNA replication
The central dogma of molecular biology is a theory that explains the flow of genetic information in an organism.
The theory originally stated that genetic information flows in three possible ways: a) DNA replication, b) transcription, c) translation.
In DNA replication, the DNA molecule duplicates producing two molecules of DNA from the original one DNA molecule. The genetic information therefore passes from one DNA molecule to another.
In transcription, an RNA molecule is synthesized based on the information stored in the DNA. In other words, the DNA code (usually containing information on how to synthesize a protein) is transcribed (rewritten) into RNA. Here, the information passes from DNA to RNA.
In translation, a protein is synthesized from the transcribed RNA molecule. The information therefore passes from RNA to protein.
The theory stated that genetic information passes in a one-way information pathway, which means that it is not possible to synthesize DNA from RNA. It is also not possible to synthesize RNA or DNA from a protein.
However, it was discovered that genetic information can be passed in other ways. In retroviruses, it is possible to transfer information from RNA to DNA - this is called reverse transcription. What is more, some RNA viruses replicate their RNA - RNA replication.
This means that today it is believed that they are five possible information pathways: 1) DNA replication, 2) transcription, 3) translation, 4) RNA replication, 5) reverse transcription.
1) DNA replication (DNA → DNA)
2) transcription (DNA → RNA)
3) translation (RNA → protein)
4) RNA replication (RNA → RNA)
5) reverse transcription (RNA → DNA)
References:
Pierce, B. A. (2019). Genetics: A Conceptual Approach (Seventh ed.). W. H. Freeman.