What is the central dogma and who challenged it?

Answer 1

The term "central dogma" of molecular biology is often taken to mean the flow of information from the DNA in the nucleus of the cell, into messenger RNA via transcription, and thence into proteins (more correctly, polypeptide chains) via translation at ribosomes in the cytoplasm.

1. The DNA replicates its information in a process that involves many enzymes: replication.

2. The DNA codes for the production of messenger RNA (mRNA) during transcription.

3. In eukaryotic cells, the mRNA is processed(essentially by splicing) and migrates from the nucleus to the cytoplasm.

4. Messenger RNA carries coded information to ribosomes. The ribosomes "read" this information and use it for protein synthesis. This process is called translation.

* * *

If this question is taken to refer to the above sense of "central dogma", and the "challenge" therefore to the "reverse" flow of information: from RNA to DNA, that was found to be routine in retroviruses (such as HIV, which causes AIDS), using the enzyme reverse transcriptase. The names of David Baltimoreand Howard Temin are particularly associated with the discovery of this enzyme.

In fact, this question opens a can of worms! It's all to do with what people take the term "central dogma" to mean.

In 1958 Francis Crick coined two terms for two ideas that were then considered fruitful in guiding future research. This was five years after the publication of Watson and Crick's double-helix model for DNA, and three years before the genetic code began to reveal itself through experiments by Nirenberg and Matthaei ("polyU" coding for phenylalanine, etc.) and by Crick and Brenner (the code consisting of three nucleotides).

The two ideas were:

1

The sequence of residues in DNA informs the biosynthesis of proteins (we would now say polypeptides), specifically the sequence of residues (amino acids). Logically enough, Crick called this idea the sequence hypothesis.

2

Once information (about the sequence of residues) has passed into a protein, it does not come out; in other words, the amino acid sequence of a polypeptide chain does not influence the synthesis of DNA, RNA, or other polypeptide chains. Crick called this the central dogma.

In later years, among other things:

Watson published a book, Molecular biology of the gene, in which he confused Crick's two points, using the term "central dogma" in a way that relates it to the sequence hypothesis. Watson did not use the term "sequence hypothesis". There has now developed a widespread myth, especially associated with the United States, that the idea of the sequence hypothesis was calledby Crick the "central dogma".

Some people who had not read Crick's paper, and knew little of his mind and modus operandi as a scientist, accused him of trying to stifle research, by being "dogmatic" that information could flow only from DNA to RNA to protein, and never in the reverse direction. Crick never said that, as a read of his 1958 paper confirms.

Crick wrote a note, published in Nature in 1970, trying to put the record straight. He particularly mentioned by name Barry Commoner as someone who had misquoted him (and, implicitly, someone who had used the misquotation to draw false conclusions about Crick's reasoning and motives).

Crick much later admitted that when he chose the word "dogma" he thought it was more or less close in meaning to "hypothesis".

Does Crick's central dogma hold true? NO. 1.) A viruses genome consists of RNA. 2.) The process of DNA to RNA to protein can actually be reversed (aka complementary DNA).

Prions do not challenge Crick's dogma. The modifications to proteins that prions effect are to secondary structure (coiling and so on), not to the primary structure (the amino acid sequence).

***

Crick's "Central Dogma" has been contradicted by countless experimental facts. However, "facts don't kill theories - only more advanced theories kill obsolete theories". "The Principle of Recursive Genome Function" (Pellionisz, 2008) showed that by retiring the old mistaken axioms of BOTH JunkDNA and Central Dogma we accomplish the theoretical breakthrough towards "Recursive Genome Function".