Scientists believe that mitochondria may have evolved from ancient bacteria because

Because of the resemblance of mitochondria to bacteria in neurones and other parts of human body. Hope this helps

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass