DNA160-page13 - correct nucleotides assuming there is an...

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DNA: Structure and Replication - 13 Proofreading DNA DNA pairing errors occur during DNA replication. Despite the complementary base pairing, mistakes can and do happen. As you might expect, DNA is proofread by DNA polymerase as it is being replicated. If there is a base-pairing error, it deletes the mistake, and replaces it with the correct nucleotide. Repairing DNA Damage Damage to DNA molecules occurs daily by exposure to routine molecules in the environment, and even to normal body temperatures. DNA repairing enzymes cut out the damaged or mutated DNA and DNA polymerase and ligase fill in the gap with
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Unformatted text preview: correct nucleotides, assuming there is an undamaged DNA strand to serve as the template. Even so, some mistakes do not get repaired. About 1 in 1 billion DNA base pair errors are not caught. Such DNA changes are known as mutations. Deterioration of DNA replication accuracy is likely a contributing factor in aging and in cancer. Exposure to UV light can cause DNA damage, which is why those who tan are at greater risk for skin cancer....
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