[ExI] Why genes don’t hold all the answers for biologists

[Adrian Tymes]

No, there is consensus on what genes are: small groups of amino acids
in DNA or RNA.  Though most genes don't result 1-to-1 in
characteristics; most characteristics are the result of several genes.

On Tue, Mar 27, 2018 at 7:19 AM, BillK <pharos at gmail.com> wrote:
> Despite being central to the subject for over a century, there has
> never been a universally accepted, constant definition of what genes
> actually are. From the beginning, scientists have tried to link human
> characteristics to genes, but had limited success in establishing
> stable connections.
>
> <https://theconversation.com/why-genes-dont-hold-all-the-answers-for-biologists-92194>
>
> Quote:
> As a consequence, the function of genes is now understood to depend on
> systems of epigenetic inheritance and environmental signalling.
> Whether a gene is activated (or not) to produce a protein depends on
> how it is “packaged” into chromosomes, and information the organism
> receives from the environment.
>
> The most important insight associated with the discovery of the gene
> in the early 20th century was that the order in which genes operate
> does not reflect the order in which the human (or plant or animal)
> body develops. One gene is not linked to one physical trait – many
> genes control many traits. Likewise, a single trait is often
> controlled by hundred of genes forming complex networks of
> interaction.
>
> With the subsequent identification of DNA as the hereditary material
> in 1953, it became possible to directly access and manipulate the
> genetic code. Even with this discovery, however, it turned out that
> genes are not well-defined stretches of DNA that translate directly
> into the structure of proteins.
>
> Genes may consist of separate building blocks that are distributed
> over the genome and have different functions. They may overlap and be
> read in a variety of ways. Their products in turn, may be cut into
> pieces and then spliced together again in a variety of ways. All of
> these activities depend on a variety of signals – from within the
> cell, from other cells, or from the environment.
> ---------------
>
> So it now turns out that gene expression is both nature *and* nurture.
> Well, who'd have thought that!
>
> BillK
>
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