Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bistability of the lac operon during growth of Escherichia coli on
  lactose and lactose + glucose   The lac operon of Escherichia coli exhibits bistability. Early studies showed
that bistability occurs during growth on TMG/succinate and lactose + glucose,
but not during growth on lactose. More recent studies with lacGFP-transfected
cells show bistability with TMG/succinate, but not with lactose and lactose +
glucose. In the literature, these results are attributed to variations of the
positive feedback generated by induction. Specifically, during growth on
TMG/succinate, induction generates positive feedback because the permease
stimulates the accumulation of TMG, which, in turn, promotes the synthesis of
more permease. This positive feedback is attenuated during growth on lactose
because hydrolysis of lactose by galactosidase suppresses the stimulatory
effect of the permease. But the stabilizing effect of dilution also changes
dramatically as a function of the medium composition. For instance, during
growth on TMG/succinate, the dilution rate of the permease is proportional to
its activity, $e$, because the specific growth rate is independent of $e$.
However, during growth on lactose, the permease dilution rate is proportional
to $e^2$ because the specific growth rate is proportional to the specific
lactose uptake rate, which in turn, proportional to $e$. Here, we show that:
(a) This dependence on $e^2$ creates such a strong stabilizing effect that
bistability is virtually impossible during growth on lactose, even in the face
of positive feedback. (b) This stabilizing effect is weakened during growth on
lactose + glucose because the specific growth rate on glucose is independent of
$e$, so that the dilution rate once again contains a term that is proportional
to $e$. We discuss the experimental data in the light of these results.

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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: hep-ph
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The categories of this paper are: funct-an
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The categories of this paper are: physics
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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-lat
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th