The XPA gene
provides instructions for making a protein which repairs damaged DNA ¾ DNA can be damaged by ultraviolet (UV) rays from
the sun and by toxic chemicals, radiation, and unstable molecules called free
radicals. DNA damage occurs frequently, but normal cells are usually able to
fix it before it can cause problems. One of the major mechanisms that cells use
to fix DNA is known as nucleotide
excision repair (NER). As part of this repair mechanism, the XPA protein
helps verify DNA damage and stabilize the DNA as it is repaired. The XPA
protein binds (attach) to areas of damaged DNA, where it interacts with many
other proteins as part of a large complex mechanism. Proteins in this complex
unwind the section of DNA where the damage has occurred, snip out (excise) the
abnormal section, and replace the damaged area with the correct DNA.
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