Putting quotes around something is called scare quotes. They are only used when:
a) the term is being used in a non-standard way
b) to mark off irony
I assume that you are not using "bar" in an ironic context, so it boils down to a question: are you using "bar" in a non-standard way? For example, you wouldn't put quotes around the following:
DNA is sometimes divided into nucleotides.
You would use quotes if you said:
DNA is sometimes divided into "letters."
Because "letter" is a non-standard term in the context of DNA, it needs scare quotes.
If you are trying to emphasize a word/phrase, never use quotes! Use italics instead.