Apostrophe vs. Single Quotation Mark
A quick refresher:
Jane said, "I like the word 'awesome.'"
Bubba said, "Stop your cussin'."
Note how both those sentences are punctuated. They end differently, yet they're both correct. Why? Because the first one has a single quotation mark before the regular double quotation mark, but the second one has an apostrophe.
A single quotation mark works just like a regular quotation mark. In American English, they both come after a period or comma. But an apostrophe represents a dropped letter. It's part of the word. So it wouldn't make sense to separate it from the rest of the word by putting a period before it.
And if you can master that, it'll put you ahead of about half the professional editors I know!