Originally posted by sonhouse
Those same genes might be repository of survival techniques like reaction to cold or heat or other environmental stresses. They may activate when the person is confronted by some unusual condition.
Precisely. Although the Intron sequences themselves lack the necessary codons to
for transcription. They do contain binding elements which can play an important
role in DNA expression.
When the Human genome project was complete it came as a surprise how fewer genes
there were compared to expectations. The reason is that many genes are recombinant.
(It's precisely what it sounds like, mis-matching gene sequences together to provide combinations)
This is especially true in the immune system which gives rise to our ability to
resist so many types of disease.
It is a myth, for example, that if an Alien came to earth we could be infected with Alien viruses
and/or bacteria. Alien viruses capable of attacking our immune systems would
stand the same or even less advantage than the pathogens we already have on
earth, even if they were designed to utilize our cellular apparatus.
'The most common type of intron is called a spliceosomal or nuclear intron; the name comes from the cellular machinery, known as the spliceosome, which is responsible for splicing and making sure that the genetic sequences in introns are not translated into junk proteins. This type of intron is the one found in the nuclear genes of humans........
There are also cases in which introns contain genes for small nuclear RNA, which is important for the translation of messenger RNA, an intermediary between DNA and proteins. Nuclear introns can also be important in a process called alternative splicing, which can produce multiple types of messenger RNA from a single gene. Although these examples demonstrate a constructive role for introns, they cannot explain why introns are so ubiquitous in our genes..'
It has been shown that the IME (intron-mediated enhancement) is particularly
sensitive to changes in the concentration of nucleotides.
'Not all introns enhance gene expression, but those that do typically enhance expression between 2– and 10–fold relative to an intronless control.'
'The sequences of the enhancing UBQ10 intron and the non-enhancing COR15a intron were modified to create large alterations in IMEter score via minimal nucleotide changes.'
So changes such as diet or sunlight can alter the production of some nucleotides
and thereby influence protein synthesis by moderating Intron Mediated Enhancement.