Describe how repair enzymes act to correct mutations and errors that occur during replication.
dont you think i tried that already. :/
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/D/DNArepair.html
Repair enzymes play a crucial role in correcting mutations and errors that occur during DNA replication. One such repair mechanism is known as mismatch repair.
During DNA replication, mistakes can occur when the wrong nucleotide is inserted into the newly synthesized strand, resulting in a base-pair mismatch. Mismatch repair enzymes detect and correct these errors.
The first step in mismatch repair involves recognition of the mismatch. This is accomplished by a group of proteins that scan the newly synthesized DNA strand, searching for any irregularities. One of the key proteins involved is called MutS, which binds to the mismatched base pair.
After recognition, a second protein called MutL is recruited, which helps coordinate the repair process. MutL interacts with other proteins, including a nuclease enzyme called MutH.
MutH acts as a molecular scanner and identifies the parental DNA strand by detecting a specific DNA sequence near the mismatch called a hemi-methylated site. Once the parental strand is identified, MutH makes a cut near the mismatch on the newly synthesized DNA strand.
The cut generates a temporary gap in the DNA molecule. Other repair enzymes, including exonucleases and DNA polymerases, are then recruited to the gap to remove the segment containing the mismatch and resynthesize the DNA with the correct nucleotides.
Finally, the newly synthesized DNA is ligated to the existing DNA strand, ensuring seamless repair and restoration of the correct base pairing.
By employing this sophisticated repair mechanism, cells can maintain the integrity and fidelity of their genetic information, minimizing the occurrence of mutations and ensuring accurate replication of DNA.