Snarf,
I know exactly what you are going through. I have a 13 yr old and 11 1/2 yr old that is trying to be like her big sister. I am also a youth worker who forgets that my kids are typical to all the other teens.
Geez, it can get depressing sometimes. All the yelling, threats, let downs, etc. It's really good you asked for help.
One thing I vividly remember my mom doing when I was growing up was that she put anything that way just left around the house into a brown paper bag. If we wanted those items, we had to do a chore to earn them back.
Another great thing is to have her work WITH you. Ask her to come along side you and help you make dinner sometime. She might whine the whole time but try to ignore it as much as possible and stick it out. Then she can complete a project with you and enjoy the finished project.
Hope this helps. I feel for you.