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

[BillK]

That's like saying Shakespeare's writings are just small groups of
letters in various arrangements.  :)  It's true but not explaining
very much.

My understanding is that he is saying that a gene is not like an
ON/OFF switch for things like blue eyes, ginger hair, etc. A gene is
more like an assembly of Lego bricks that can join on to other Lego
bricks, or split up and recombine with other bits of Lego, or just be
ignored in the construction kit.  So any particular gene may
contribute to many different functions, (or none), depending on how it
is expressed.
The full article (and the book) explains what he is trying to say.

Quote:
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.

It is these insights into genetic mechanisms which made a single rigid
definition of the gene impossible. Instead, experimental systems were
developed in which genes were defined flexibly in order to track
processes involved in the development and evolution of organisms.
What it is to be a gene varies widely, just as everything else does in
biology, since genes are not so much autonomous units of life, but
themselves a product of evolution.
-----------

BillK


On 28 March 2018 at 19:15, Adrian Tymes <atymes at gmail.com> wrote:
> 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
>>
>> _______________________________________________What it is to be a gene varies widely, just as everything else does in biology, since genes are not so much autonomous units of life, but themselves a product of evolution.
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