a quick question on Biology.

[Crunchee]

1.Do mature red blood cells have VERY FEW mitochondria or NONE?
2.Do MATURE red blood cells have NO nucleus but the IMMATURE red blood cells have one?
3.Does rough ER (endoplasmic reticulum with ribosomes attached to the surface) do anything other then being a site of protein synthesis?

Thanks
Btw, don't ask me why don't I google them myself, I just want to ask the nicest forumers in the world and this isn't that urgent