Ethidium binds to DNA. Ethidium ion is also largely flat. Ethidium ion intercalates Intercalation is the reversible inclusion/insertion of a molecule (or group) between two other molecules (or groups) This insertion would cause DNA to become mutated, since it might replace nucleotides Solution Ethidium binds to DNA. Ethidium ion is also largely flat. Ethidium ion intercalates Intercalation is the reversible inclusion/insertion of a molecule (or group) between two other molecules (or groups) This insertion would cause DNA to become mutated, since it might replace nucleotides.