Question

Given current research discoveries and trends in biology, is the traditional notion of a gene as a biological unit of inheritance that has a specifically identifiable location in a cell obsolete?

Answer 1

First of all, I'd like to point out that by not specifying precisely which "current research discoveries and trends in biology" you mean, people can and do many different things by this question and come up with many mostly contradictory (and often very pseudoscientific) answers.

Until you specified "in a cell" the question was quite interesting.

The alleles for each gene have an actual, physical location on the arm of a chromosome. The chromosome sits in the cell and - depending on the resolution of your experimental system, like a tagged transcription factor specific for that gene which flouresces when bound its target DNA - you can tell where exactly in the cell the gene actually is. In what way has current research possibly made that idea obsolete?

Is the single gene still the functional unit of inheritance? If you define 'gene' to be a DNA sequence which codes for an mRNA, then no. If you define 'gene' to be a DNA sequence which codes for an RNA molecule - be it a tRNA, siRNA, rRNA, microRNA or any kind of RNA - then it's certainly open to debate. According to the RNA world hypothesis, in the beginning everything was RNA - then cells evolved DNA specifically to store information and proteins as more highly specialized and efficient molecular machinery.

And then there is the so called non-coding DNA, which was one of the big surprises in the human genome project. This lot likely has structural purposes - like repeated regions at the ends of telomeres which protect against loss of coding genetic material through multiple rounds of replication and repeats which give the DNA certain local structures (because within the loose concept of "double helix" there is a lot of variation in actual local structure, conformation and topology) conductive to proper chromatin formation and DNA processing.

Is that an answer to what you were asking?

Answer 2

Unlike many other forms of discourse, such as in politics, certain observations in science simply do not change, because it turns out that is just how the world works. For example, there is not a "theory of evolution". Evolution is a fact, and is a theory in so much as there is a "theory of gravity". This means that over the years, numerous tests have been conducted, by many different people, all showing that these things are reproducible and exist. The genes are arranged in a linear fashion on chromosomes, and are the units of selection for natural selection, as well as inherited to the next generation is another such fact. Of course the subtleties may change.