Question

Study the diagram given and answer the question.
Why have DNA fragments in band 'D' moved farther away in comparison to those in band 'C'.

Answer 1

In gel-electrophoresis the DNA fragments move according to their size, with the smaller fragments travelling further in the gel and the band appearing lower in comparison to larger DNA fragments that move slower in the gel and cannot move far. As a result of this, the band formed of such large DNA fragments appear at the top (i.e near the cathode). Hence, movement of fragment D further in the gel indicates that it is formed of smaller fragments and the fragment C that does not move far is formed of larger sized DNA fragments.