Does the cell
use a language like the brain or like a computer?
These are three very different arrangements of symbols into strings. By 'sequence' I mean protein sequence; language is necessarily English-like (not pictorial); code is whatever - but probably a 'normal' language.
Computer code is generally brittle - that is, intolerant to change. If you make a single important typing mistake in many, many lines the program will probably fail. Of course, good design tries to minimise the effects, but it's not built in.
Sequence mutates; to cope with this, the structures the protein can form are often degenerate. To make an analogy to code, sequence almost always 'executes' (on the physics hardware:) but exhibits polymorphism. Unfortunately, the 'result' (the product) of such an evolutionarily designed program is not guaranteed to be the same.
Language evolves; language is like a river. Meanings of words can change over time, continuously and smoothly. However, words are not as context dependant as sequence. They chunk nicely so that while letters can mean very different things in the context of a word, words are relatively constant in sentances.
In conclusion, sequence is a code that is malleable and infinately extensible yet highly dependant on context. This allows it to change and produce novel, workable results.