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.
When errors occur during nucleotide sequencing, the correct answer is d. DNA polymerase proofreads for errors while another enzyme corrects them.
To understand why d is the correct answer, let's break down the options:
a. DNA polymerase replaces the incorrect nucleotide with the correct one: DNA polymerase is an enzyme responsible for adding nucleotides to a growing DNA strand during replication. While it can add the correct nucleotide, it does not "replace" incorrect nucleotides on its own.
b. Enzymes dissolve the incorrect nucleotide so DNA polymerase can add the correct one: While enzymes are involved in various DNA processes, dissolving incorrect nucleotides is not a mechanism for error correction during nucleotide sequencing.
c. Purines replace pyrimidines in the DNA molecule: This answer is incorrect because purines (adenine and guanine) and pyrimidines (thymine and cytosine) are types of nucleotide bases present in DNA but they do not replace each other during sequencing.
d. DNA polymerase proofreads for errors while another enzyme corrects them: This is the correct answer. DNA polymerase has a proofreading mechanism where it checks each nucleotide it adds for errors. If a mistake is detected, DNA polymerase can remove the incorrect nucleotide and replace it with the correct one. Additionally, another enzyme called exonuclease is responsible for editing and correcting errors in the DNA sequence. This two-step process helps to ensure accuracy in nucleotide sequencing.