Question

The process of polymerase chain reaction most closely mirrors to that of

A. Replication
B. Transcription
C. Translation
D. Meiosis

Answer 1

Hint: This technique allowed DNA sequences to be amplified in vitro using pure enzymes. The great sensitivity and robustness of the PCR allow DNA to be prepared rapidly from very small amounts of starting material.

Complete step by step answer: The first step of the PCR is an initialization, where the thermocycler is heated so that the DNA polymerases are activated. The next step is denaturation, where the two strands of DNA template are denatured by breaking the hydrogen bonds at around 94°C- 98°C. Now, in the annealing step, the forward and reverse primers are attached to the complementary templates at around 50°C -65°C. In the next step, the extension of the new template takes place. From the 5’ to 3’, Taq polymerases allow the synthesis of the new strand complementary to the template strand with the help of primers at 75–80 °C. The PCR occurs in vitro in a thermocycler.
i. Replication is the synthesis of new DNA strand from its complementary template strand in vivo using the replication machinery including helicase, primers, DNA polymerase. It involves steps like initiation, elongation and termination. The DNA synthesis has directionality and can the replication fork can form a leading strand and a lagging strand.
ii. The transcription is a process in which the mRNA is formed from the template DNA strand using the transcriptional machinery in vivo. There is no amplification of the DNA template. Functional mRNA is formed instead.
iii. Translation is the process where a protein chain is formed from the mRNA using the translational machinery using ribosomes and the open reading frame of mRNA along with other enhancers and activators.
iv. Meiosis is the formation of four cells from a single cell. It occurs in germ cells where the genes are inherited from both father and mother.
Hence, the correct answer is option A.

Note: The PCR method was first proposed by H. Khorana and his colleagues in the early 1970s to lessen the labour involved with the chemical synthesis of genes. However, it was not accepted during that time. After 15 years the technique was independently developed by Kary Mullis and his co-workers and given its present name Polymerase Chain Reaction.