How to get my sister to do what she's supposed to?

My sister does her chores \*sometimes*\ on her own, but really only when someone tells her to. Even worse, my mom is out of town and my dad is at work during the day. I've been left to feel that I have to clean up after everything, whether it's my sister's responsibility or not--and I have online school to work on during all of this. I've called her out on it and told her that she needs to pick up after herself and be aware of anything that needs to be done. I've even told her I realize I'm being bossy but I wouldn't need to say anything if she did what she was supposed to in the first place. But she keeps telling me I'm getting too uptight and getting into yelling matches with me. I've tried being nice, I've tried telling my parents, I don't know what to do! She's really pissed and won't listen to me. It's wasting both of our time and draining my energy. I just don't want our parents to come home to a mess.