Figure 27.15. Proofreading.

Figure 27.15Proofreading

The growing polynucleotide chain occasionally leaves the polymerase site of DNA polymerase I and migrates to the exonuclease site. There, the last nucleotide added is removed by hydrolysis. Because mismatched bases are more likely to leave the polymerase site, this process serves to proofread the sequence of the DNA being synthesized.

From: Section 27.2, DNA Polymerases Require a Template and a Primer

Cover of Biochemistry
Biochemistry. 5th edition.
Berg JM, Tymoczko JL, Stryer L.
New York: W H Freeman; 2002.
Copyright © 2002, W. H. Freeman and Company.

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