Biology Reference
In-Depth Information
involved in one of these phenomena and isolate other proteins that
interact with it; it should be possible to analyse, therefore, the cas-
cade of molecular interactions that determine it
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and thus be able to
fully explain it. From a protein, it should be possible to reconstitute
the entire causal chain underlying the phenomenon. This is why the
analysis of a biological process always starts by isolating a protein
(or the corresponding gene) implicated in that process. This theory
justifies the genome sequencing programme which should lead to
our acquiring every bit of information relating to these stereospe-
cific proteins and the organisms they produce.
3.3 Genetic programming and signalling
Stereospecificity is also a key concept for understanding how genetic
programming functions. Although this raises a great many prob-
lems, the genetic programme was conceived by analogy with a com-
puter program (Longo and Tendero, 2007). According to genetic
theory, cells differentiate because the different sets of genes which
are active in the various types of cells confer particular morpholog-
ical and functional properties on them (Morgan, 1934). To explain
this, it has been assumed that some genetic information controls
how the genome itself functions. There are said to be two types of
genes: structural genes encoding for the proteins directly involved
in the construction of cells or how they function, such as membrane
proteins or enzymes, and regulator genes, controlling the activity of
these structural genes. According to the theory of genetic program-
ming, the regulator genes are responsible for the differential expres-
sion of genes, because they code for the proteins which act as
signals to activate or inhibit the structural genes. Their own regu-
lation during cell differentiation corresponds to the genetic pro-
gramme of the organism. However, for this theory to be acceptable,
it is necessary to explain in concrete terms how these signals, which
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This is possible since techniques for finding the molecular partners of a protein
are available now.
