How Is The Central Dogma Evidence For Evolution?
Written By,Ronit Dey - (B.S in Zoology)
The theory of chemical evolution states the formation of organic molecules from inorganic ones. Oparin and Haldane proposed this theory which is also called a chemical theory.
This theory states that first life originated from pre-existing, non-living organic molecules like RNA, proteins, etc. by chemical evolution. i.e. the formation of organic molecules from inorganic ones.
This chemical theory is explained dedicatedly by the Oparin-Haldane hypothesis suggesting that life arose gradually from inorganic molecules, with building blocks of life like amino acids forming first and then combining to make complex polymers like proteins.
--
At an early stage, life consisted of a self-replicating RNA system
It has been proposed that, at an early stage, life consisted of a self-replicating RNA system, and that DNA and proteins evolved later. This is in accordance with the RNA world hypothesis.
According to this RNA world hypothesis, simpler biopolymers came first and those evolved the ability to catalyze the production of RNA, which then took over the genetic control of the first formed simple living organisms.
Earlier that RNA was self-replicating and was a very stable-versatile compound in the ancestral first formed organisms and had the ability to control the genetic needs.
RNA had the capacity to help itself even further by segregating or synthesizing its own building blocks.
RNA was able to self-replicate and also able to catalyze the formation of various proteins but was non-living in nature.
In some present-day viruses (retroviruses), RNA is still the genetic compound as it was during the early days of evolution.
In retrovirus, the genetic flow of information is in reverse direction i.e from RNA to DNA.
RNA of the retroviruses first synthesizes DNA in the presence of Reverse Transcriptase enzyme. DNA then transfers information to RNA and the translation occurs. This is called the central dogma reverse model.
The presence of RNA makes the retroviruses still non-living. So, if the retrovirus enters a host cell it becomes living and can create a DNA pro-virus by reverse transcription mechanism.
That DNA pro-virus can replicate and form an RNA in the host cell which will later translate to proteins. And, those proteins can show the retroviral genetic traits in the host cell.
Mutation in accordance to Central Dogma
A gene mutation is a permanent alteration in the DNA base sequence, such that the sequence differs from what is found in most people or from its parents.
Mutations occur in very rare cases but, it does occur and had been occurring quite a few times during the course of evolution.
In rare cases, during a person’s life span there may be few cells where the mutation occurs.
These mutational changes can be caused by environmental factors such as UV from the sun, chemical factors, replication mistakes, or can occur if an error is made as DNA copies itself during cell division.
For example: In the human genome, there are over 3.1 billion bases of DNA, and each base must be faithfully replicated for cell division to occur. Mistakes, although surprisingly rare, do happen. And so about one in every 1010 (10,000,000,000) base pair is changed due to mutations as the DNA is passed to the next generation.
Another Example: The history of the gray treefrog, Hyla versicolor, is an example of mutation and its potential effects. When an ancestral Hyla chrysocelis gray treefrog failed to sort its 24 chromosomes during meiosis, the result was H. versicolor. This treefrog is identical in size, shape, and color to H. chrysocelis but has 48 chromosomes and a mating call that is different from the original H. chrysocelis.
These above examples show that mutation can occur in nature rarely. And, if occurred in an organism it changes the genetic sequence a bit.
And, if mutations had occurred again and again during the millions of years of history in the same organism, it can change the genetic sequence a lot and so can create new life forms that is new species.
Mutated DNA are altered DNA that will create a new type of mRNA and so new type of proteins showing different genetic traits, than the original life form. Thus, forming new species.
When a mutated DNA sequence is formed, that mutated DNA can self-replicate and produce more copies. These copies will form RNA and so RNA will later form Proteins. That’s in accordance with the Central Dogma Model.
Thus mutation is also helpful in understanding the Central Dogma’s evidence for evolution.
https://onlyzoology.com/how-is-the-central-dogma-evidence-for-evolution/