Question

PCR : _____I_____
Gel electrophoresis : _____II_____

• A. I - Amplification of DNA molecule,
  II - Separation of DNA molecules on the basis of size
• B. I - Separation of DNA molecules on the basis of size,
  II - Amplification of DNA molecule
  
• C. I - Cleavage of DNA molecule,
  II - Amplification of DNA molecule
  
• D. I - Separation of DNA molecules on the basis of size,
  II - Cleavage of DNA molecule

Answer 1

The correct option is A I - Amplification of DNA molecule,

II - Separation of DNA molecules on the basis of size
Polymerase chain reaction (PCR) is a technique where a specific sequence of DNA can be amplified. It involves the use of pre-designed primers. These, then undergo cycles of denaturation, annealing and extension which gives an amplified amount of the parent DNA sequence.

Gel electrophoresis is a laboratory technique based on the principle of movement of charged particles towards oppositely charged electrodes under the influence of electric fields. The technique is widely used for the separation of a mixture of DNA (a negatively charged molecule) fragments of varying sizes on agarose gel (a natural biopolymer) matrix under the influence of an electric field. DNA, being negatively charged, migrates towards the anode (positively charged terminal) in the electrophoresis unit.

Cleavage of DNA molecules is accomplished by the treatment with restriction enzymes. Restriction enzymes are the molecular scissors which cleave a DNA molecule at specific sequence. Cleavage of a DNA molecule yields several fragments, each containing a specific number of base pairs. The process is known as restriction digestion.