Question

How many time needed for PCR?

Hint:

PCR is typically completed in about an hour, depending on the number of cycles and the efficiency of the reagents used.

Answer 1

Polymerase Chain Reaction (PCR) completion generally spans 1 to 3 hours, contingent on the protocol and equipment employed. The PCR procedure comprises distinct phases, each with a defined duration.

PCR Stages and Their Durations:

• Denaturation: This phase typically lasts approximately 20-30 seconds at temperatures between 94-98°C, serving to separate double-stranded DNA into two single strands.
• Annealing: This phase typically lasts 20-40 seconds at temperatures around 50-65°C, during which short DNA primers attach to complementary sequences on the single-stranded DNA templates.
• Extension (Elongation): This phase requires about 1-2 minutes at 72°C for the DNA polymerase enzyme to extend primers by incorporating nucleotides, thereby synthesizing new DNA strands. The duration is dependent on the size of the DNA target (approximately 1 minute per 1,000 base pairs).

Additional Factors:

• Cycle Count: A standard PCR reaction involves 20-40 cycles of denaturation, annealing, and extension. Each cycle takes roughly 3-5 minutes, so the total amplification time varies with the cycle count.
• Efficiency Enhancements: Advanced PCR instruments, such as thermal cyclers, can accelerate the process through optimized temperature transitions, potentially reducing the overall PCR run time.

In summary, PCR typically requires approximately 1 to 3 hours, influenced by protocol specifics, including DNA target length and the number of cycles performed.