17. When errors in nucleotide sequencing occur,
a. DNA polymerase replaces the incorrect nucleotide with the correct nucleotide
b. enzymes dissolve the incorrect nucleotide so DNA polymerase can add the correct one
c. purines replace pyrimidines in the DNA molecule
d. DNA polymerase proofreads for errors while another enzyme corrects it
[The link from yesterday didn't really help me find my answer...I think it is A]
Thanks
-MC
The correct answer is:
d. DNA polymerase proofreads for errors while another enzyme corrects it.
During the process of nucleotide sequencing, DNA polymerase adds complementary nucleotides to the growing DNA strand. However, errors can occur in this process. To ensure accuracy, DNA polymerase has a proofreading function that allows it to detect and correct errors. It checks whether the newly added nucleotide is properly base-paired with the template strand. If an incorrect nucleotide is detected, DNA polymerase removes it and replaces it with the correct nucleotide. This proofreading process helps to minimize errors in nucleotide sequencing.
Option A is correct. When errors occur during nucleotide sequencing, DNA polymerase has the ability to proofread and correct the mistake.
DNA polymerase is the enzyme responsible for adding nucleotides to the growing DNA strand during replication. It has a built-in proofreading mechanism called 3' to 5' exonuclease activity, which allows it to detect and correct errors.
Here's how it works:
1. During DNA replication, DNA polymerase attaches to the template strand and starts adding complementary nucleotides to the growing daughter strand. It moves along the template strand in the 3' to 5' direction.
2. If the incorrect nucleotide is added, DNA polymerase can detect the mismatch through its proofreading activity.
3. The enzyme then removes the incorrect nucleotide using its 3' to 5' exonuclease activity. This activity allows DNA polymerase to "back up" and remove the last nucleotide it added.
4. Once the incorrect nucleotide is removed, DNA polymerase then adds the correct nucleotide to the growing daughter strand.
This proofreading mechanism helps to ensure the accuracy of DNA replication by minimizing the occurrence of errors. It significantly reduces the error rate from approximately 1 in every 10,000 nucleotides to about 1 in every 100 million nucleotides.
I hope this explanation clarifies your understanding! If you have any further questions, feel free to ask.