Complex sentence: Psychrophiles also create antifreeze proteins to keep their internal space liquid, and to protect their DNA when temperatures drop to water's freezing point; the proteins prevent any ice formation or recrystallization process from occurring on the organism.
Split into simpler sentences: Psychrophiles also create antifreeze proteins to keep their internal space liquid, and to protect their DNA when temperatures drop below water's freezing point. To accomplish this, the proteins prevent any ice formation or recrystallization process from occurring on the organism.