Question

Which of the following modifications is least likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis? A) altering the nucleotide sequence of the DNA fragment B) methylating the cytosine bases within the DNA fragment C) increasing the length of the DNA fragment D) decreasing the length of the DNA fragment E) neutralizing the negative charges within the DNA fragment

Answer 1

Answer:

A) altering the nucleotide sequence of the DNA fragment

Explanation:

Gel electrophoresis is a technique to separate the DNA fragments on the basis of their charges and size. DNA fragments are made to migrate through a gel in an electric field. DNA has nucleotides and the presence of phosphate groups makes it a negatively charged molecule. In the gel electrophoresis, DNA fragment migrates through the gel toward the positive pole. Also, the gel slows down the large molecules more than the small molecules. Therefore, the DNA fragments are separated by size. However, the sequence of the nucleotide of DNA fragments does not affect the rate of their migration in the gel.