Multiple choice RCR endonucleases create a nick to create a free hydroxyl in the DNA of retroviruses adenoviruses ssDNA viruses cellular life forms Reveal answer Fill a bubble to check yourself C Correct answer Explanation The 5′ end of the nicked strand is transferred to a tyrosine residue on the nuclease and the free 3′ OH group is used by the DNA polymerase to synthesise the new strand.