Q.How is the amplification of a gene sample of interest carried out using PCR?

Step 1. Set up the reaction: the DNA sample containing the gene of interest is mixed with two specific primers flanking the target sequence, Taq DNA polymerase, the four deoxynucleotide building blocks (dATP, dCTP, dGTP, dTTP), and buffer. Step 2. Denaturation: the mixture is heated to about 95°C for a short time, splitting the double-stranded template DNA into two single strands that will each serve as a template. Step 3. Annealing: the mixture is then rapidly cooled, allowing the two primers to bind to their complementary sequences flanking the target region on each of the separated single strands. Step 4. Extension/synthesis: the temperature is raised to about 75°C, and Taq DNA polymerase extends each primer by copying the single-stranded template, leaving both original strands partially double-stranded by the end of the cycle. Step 5. Repeat: this three-step cycle is repeated again and again — typically 25 to 75 times — and because every new strand made in …

Walk through the three-step PCR cycle in order and explain why repeating it produces …

• Describing PCR as a single-pass reaction rather than a repeated, exponential cycling process. …