Question

DNA fragments are,
(a) Either positively or negatively charged depending on their size
(b) Positively charged
(c) Negatively charged
(d) Neutral

Answer 1

 Hint: DNA or Deoxyribonucleic Acid is a molecule composed of polynucleotide chains and acts as the genetic material. The DNA fragments have phosphate ions which are electron-rich and are charged correspondingly.

Complete Step by Step Answer:
DNA is the hereditary material in humans and almost all other organisms. The DNA fragments have Phosphate ions which are negatively charged due to additional electrons and due to that, the whole DNA fragment is imparted a negative charge.
So, the correct answer is, “Negatively charged.”

Additional Information: The DNA fragments are separated by a process known as the Gel electrophoresis. The process of gel electrophoresis separates the fragments based on their size and charge. Nucleic acid molecules are separated by applying an electric field to move them through a matrix of agarose or other substances. Since the DNA molecules are negatively charged the move towards the positive terminal of the field. The smaller chromosomes and particles move faster through the matrix and travel farther whereas the longer chromosomes move sloppily and do not move very far. Thus this process also allows us to arrange the chromosomes according to their sizes and they are named accordingly from chromosome 1 which is the largest, through chromosome 22 which is the smallest of the autosomes.

Note:
- During the gel electrophoresis procedure, the Shorter molecules move faster and migrate farther in the agarose medium than the longer ones because shorter molecules migrate more easily through the pores present in the gel. This phenomenon is called sieving.
- Gel electrophoresis is a process used to separate all kinds of macromolecules that is DNA, RNA, and proteins. It may sometimes be used to separate nanoparticles too.