Question

What is a primer and how does it enable PCR?

Answer 1

PCR is Polymerase chain reaction is a method used in molecular biology to rapidly make millions to billions of copies of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it to a large enough amount to study in detail. It is fundamental to many of genetic testing including analysis of ancient samples of DNA and identification of infectious agents. PCR, copies of very small amounts of DNA sequences are exponentially amplified in a series of cycles of temperature changes. PCR is now a common and often indispensable technique used in medical laboratory and clinical laboratory research for a broad variety of applications including biomedical research and criminal forensics.The components required for PCR include a DNA sample, DNA primers, free nucleotides called ddNTPs, and DNA polymerase.

.PCR primers:-They are short fragments of single stranded DNA and it is 15-30 nucleotides in length.Thay are complementary to DNA sequences that flank the target region of interest. The purpose of PCR primers is to provide a “free” 3'-OH group to which the DNA polymerase can add dNTPs.The forward primer attaches to the start codon of the template DNA (the anti-sense strand), where as the reverse primer attaches to the stop codon of the complementary strand of DNA (the sense strand). The 5' ends of both primers bind to the 3' end of each DNA strand.