DNA Nucleotide Damaged by Oxidation (image) NIH/National Institute of Environmental Health Sciences Share Print E-Mail Caption After the DNA polymerase (gray molecule in background) inserts a damaged nucleotide into DNA, the damaged nucleotide is unable to bond with its undamaged partner. As a result, the damaged nucleotide swings freely within the DNA, interfering with the repair function or causing double-strand breaks. These steps may ultimately lead to several human diseases. Credit Bret Freudenthal, NIEHS Usage Restrictions For stories about this press release only Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.