  We discuss how information encoded in a template polymer can be
stochastically copied into a copy polymer. We consider four different
stochastic copy protocols of increasing complexity, inspired by building blocks
of the mRNA translation pathway. In the first protocol, monomer incorporation
occurs in a single stochastic transition. We then move to a more elaborate
protocol in which an intermediate step can be used for error correction.
Finally, we discuss the operating regimes of two kinetic proofreading
protocols: one in which proofreading acts from the final copying step, and one
in which it acts from an intermediate step. We review known results for these
models and, in some cases, extend them to analyze all possible combinations of
energetic and kinetic discrimination. We show that, in each of these protocols,
only a limited number of these combinations leads to an improvement of the
overall copying accuracy.
