“Cognate” (in the context of biology) basically means “correct” – when you see it, think “recognize” because molecules are able to “recognize” their “correct” (cognate) binding partners based on them providing favorable binding interactions. “Non-cognate” (wrong) molecules won’t be able to bind stably, so interactions will typically only be transient. This is how, for example, cellular receptors are able to specifically respond to some signaling molecules but ignore others. And is how ribosomes are able to make sure they only add the right amino acid by only binding stably enough to “cognate” tRNAs.
