Answer: The nucleus.
Explanation: In an atom, there are two main parts, the nucleus and the electron cloud/electron shells. The protons and neutrons are located in the nucleus, and the electrons are located in the electron shells/cloud/whatever.
I think the scientist distinguish whether an entity is living or non living be describing the single unit of life, the live cell that could multiply, reproduce and generate trough time also through ages. I hope you are satisfied with my answer and feel free to ask for more
Genotype or Phenotype relationships
