Biotechnology- Principles and Processes Question 17
17. What is the criterion for DNA fragments movement on agarose gel during gel electrophoresis? [2017]
(a) The smaller the fragment size, the farther it moves
(b) Positively charged fragments move to farther end
(c) Negatively charged fragments do not move
(d) The larger the fragment size, the farther it moves
Show Answer
Answer : a
Hints & Solutions
(a) DNAfragments during gel electrophoresis, separate (resolve) according to their size due to sieving effect provided by agarose gel. Loading buffer is used in gel and SDS-PAGE electrophoresis in order to increases the density of the sample. DNA loading buffers contains a coloured dye and a density agent. The density agent serves to enhance the density of the DNA sample allowing the DNA to sink into the bottom of the well. The dye adds visibility to the DNA sample and also serves as a tracking dye allowing the user to monitor the DNA migration during electrophoresis.
