Biological Fluidity, a Thought
Maybe biology is not as set in stone as we are led to believe.
Defining the major misconceptions in any given field of science is often more difficult than it seems, particularly when it comes to getting down to the core of common misconceptions. For the field of biology, any number of misconceptions can be named — however, the major misconception, in my opinion, is the idea of biological rigidity.
You see, in undergraduate biology classes, we often learn the vastness of biological knowledge in a rigid fashion: DNA existing as an implicitly exclusive right-handed double stranded complementary anti-parallel helix, DNA encoding RNA encoding proteins in a forward only fashion, AUG start codon as a compulsory element needed for protein translation, etc.
However, as one’s familiarity with biology grows stronger, certain realizations come to surface. For example, very often, DNA does not exist in its B-form (a Watson-Crick double helix model). In fact, DNA can form 3 (H-DNA) or even 4 (G-quadruplex) strand interactions, it can run in a parallel direction (with both strands going 5' to 3' end), it can even be left-handed helix (Z-DNA). Additionally, besides adenine-thymine and guanine-cytosine pairing, guanines can also noncanonically base-pair with thymines. RNA can reverse-transcribe itself into DNA (as is the case with retro viruses), and even form catalytically active units (such as ribosomes). Ultimately, protein translation can begin with CAG, CUG, AUA, or AAU codons to name a few. In fact there are certain structured repetitive RNAs that can initiate translation in start-codon independent manner (phenomenon known as Repeat Associated Non-AUG translation, or RAN translation).
In fact, biology is so arguably fluid that even concepts like death are heavily debated in the community. The way I like to look at it: each cell is an infinitely complex biochemical reactor composed of immeasurable amount of interacting chemical units. Now imagine having trillions of such reactors, capable of virtually unlimited interaction — and you have yourself a human being.