Final answer:
The protein that bacteria use to form a ring at the site where the two daughter cells will separate is called FtsZ.
Step-by-step explanation:
The protein that bacteria use to form a ring at the site where the two daughter cells will separate is called FtsZ. FtsZ is structurally related to tubulin and assembles into a Z ring on the cytoplasmic membrane. This Z ring is anchored by FtsZ-binding proteins and defines the division plane between the two daughter cells.