Cheeky 7 year old...............?

Is a 7 years old too young to punish? My daughter isn't exactly , but when she does misbehave, or while I am explaining things to her she often gets a bit lippy, not rude, but she does answer back sometimes. I usually punish her by sending her to her room, taking away TV privileges or her pocket money. My family members say I am breaking her spirit that I should let her speak her mind and allow her to express her thoughts.But I don't think it's right for her to talk back to me. Am I right in punishing her when she does this?