This species of bacteria is electroreceptive, and when it receives an input pattern of electric spikes, it can “translate” that input pattern into a pattern of chemical signals internally via its receptors. This internal pattern of chemicals, represented by varying “positive” and “negative” signals, is received and “recorded” in order by an inner membrane.
Another structure within the bacterium then reads the “recording” of the chemical pattern, and depending on the specific pattern, either responds by activating or by remaining inactive. So to use a binary system as a basic representation, if the pattern 001011 is read, the cell recognizes that as a pattern to which it is supposed to activate and does so; but if the pattern 110001 is read, the cell recognizes that as a pattern to which it is supposed to remain inactive (or more accurately, just fails to recognize the pattern), and does nothing. This activation causes the opening of channels in the cell membrane, to export a signal of its own.
But since this structure doesn’t actually have a conscious mind to comprehend a variety of different patterns, how can this cell (or rather, that internal organelle that “reads” the patterns) be able to recognize a given pattern so that the programmed response can be determined? What sort of cellular/molecular structure would allow for that function to occur with multiple different, specific patterns?