How does your 17yr old repond to all this? If she laughs or just tells the little one to "get off" and calls for Mum to help, then she is sending the wrong message out. Your 2 yr old must think there is some pay off to keep doing it. What your eldest daughter needs to do is drop to eye level and firmly tell the little one "We don't bite, pinch etc" and then put her in another room for a couple of minutes. After the time has elapsed, she then needs to tell her little sister that she can come back to be with her, but if she starts her antics again, she will be removed again...and again.... Believe me it will work!
I do think that the little one really wants big sister's attention though. Maybe she could dedicate herself to playing and interacting with her for a length of time. One to one, with no distractions. At 17, she probably just wants to do her own thing and the little one feels left out and lost - biting and pinching sure gets attention and even negative attention is preferable to a child than none at all!