The image below depicts the result of gel electrophoresis


If the ladder represents sequence length upto 3000 base pairs (bp), 

  1. Which of the bands (I - IV) correspond to 2500 bp and 100 bp respectively? 

  2. Explain the basis of this kind of separation and also mention the significance of this process.


  1. Band III corresponds to 2500 base pairs, and Band IV corresponds to 100bp.
  2. The fragments will resolve according to their size. The shorter sequence fragments would move farthest from well as seen in Band IV (100 bp) which is lighter as compared to Band III which is heavier being 2500 base pairs.


The significance of electrophoresis is to purify the DNA fragments for use in constructing recombinant DNA by joining them with cloning vectors.

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.