Although it is not catalytic RNA, T. A. Steitz proposed that these enzymes use a two-divalent-metal-ionmechanism for catalysis. A nuclease and one of these enzymes is used in the technique of nick translation.The first one of these enzymes to be discovered can be cleaved by subtilisin to yield a Klenow fragment,which lacks 5-prime to 3-prime exonuclease activity. These enzymes add a deoxynucleotide to a freehydroxyl at the 3-prime end of a nucleic acid strand. Two of the most commonly used types of them are Pfuand Taq, 
Although it is not catalytic RNA, T. A. Steitz proposed that these enzymes use a two-divalent-metal-ionmechanism for catalysis. A nuclease and one of these enzymes is used in the technique of nick translation.The first one of these enzymes to be discovered can be cleaved by subtilisin to yield a Klenow fragment,which lacks 5-prime to 3-prime exonuclease activity. These enzymes add a deoxynucleotide to a freehydroxyl at the 3-prime end of a nucleic acid strand. Two of the most commonly used types of them are Pfuand Taq, which are central to a technique invented by Kary Mullis. For 10 points, identify these enzymethat are used to amplify DNA in a namesake "chain reaction."
Although it is not catalytic RNA, T. A. Steitz proposed that these enzymes use a two-divalent-metal-ionmechanism for catalysis.
DNA polymerases [or pols]