At one time, everyone knew what a gene was. It was one of those little beads on our chromosomes that determined whether we would be tall or short, fat or thin, smart or stupid. Or else didn’t, if we favoured the “environment” hypothesis.
The trouble is, in the age of genome mapping, ENCODE, epigenetics, it’s all more fuzzy and more like real life at the same time.
One friend suggested that “a gene is a functional unit of heritable information.” Perhaps it need not be a nucleotide. But for the term “gene” to be meaningful, the information must be in principle heritable, whatever the physical medium is.
Meanwhile, there is
Gerstein et al., “What is a gene, post-ENCODE? History and updated definition,” Genome Research, 17:669-681 (2007):
A proposed updated definition
There are three aspects to the definition that we will list below, before providing the succinct definition:
1.A gene is a genomic sequence (DNA or RNA) directly encoding functional product molecules, either RNA or protein.
2.In the case that there are several functional products sharing overlapping regions, one takes the union of all overlapping genomic sequences coding for them.
3.This union must be coherent-i.e., done separately for final protein and RNA products-but does not require that all products necessarily share a common subsequence.
This can be concisely summarized as:
The gene is a union of genomic sequences encoding a coherent set of potentially overlapping functional products.
Readers? What you think?
See also: It’s a sociable gene, not a selfish gene (Despite that, it has unFriended Richard Dawkins.)
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