Antarctic fish. To stop their blood from freezing, some fish that live in the arctic and Antarctic have special Antifreeze proteins. Antifreeze proteins are very clever, as they slow down the formation of bonds between water molecules, which prevents the formation of ice crystals in the fish's blood.
Mutations can lead to missing or malformed proteins, and that can lead to disease. ... Some mutations happen during cell division, when DNA gets duplicated. Still other mutations are caused when DNA gets damaged by environmental factors, including UV radiation, chemicals, and viruses. Few mutations are bad for you.
mitochondria and chloroplasts, which have their own DNA and membranes, suggests that these organelles descended from prokaryotes that were engulfed by a larger cell.