Extension Time In Pcr In San Jose
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Primer length Longer primers are less efficient during the annealing step, resulting in a lower amount of PCR product.
Generally, use an extension time of 1 min/kb. If the annealing time is too short, primers do not have enough time to bind to the template. Use an annealing time of at least 30 sec. If the annealing temperature is too high, primers are unable to bind to the template.
If the annealing temperature is too low, non-specific products can be generated, leading to smeared bands on the gel. If the extension time is too long, secondary products can be formed, which can contribute to smearing.
The extension time of PCR depends upon the synthesis rate of DNA polymerase and the length of target DNA. The typical extension time for Taq DNA Polymerase is 1 min/kb, whereas that of Pfu DNA polymerase is 2 min/kb.
Extension is achieved by using the loosened nucleotides of each base to grow the complementary DNA strand. The end result is two double-stranded products of DNA. The temperature that is used during the extension phase is dependent on the DNA polymerase that is used.
Many of the common problems with PCR and RT-PCR are identified during agarose gel electrophoresis of the reaction products. These include the absence of the expected amplification product, the presence of nonspecific products, excessive smearing, and the presence of a “primer dimer” band.
Step : 3 Extension Generally, the reaction mixture is heated to a temperature intermediate between denaturation and annealing at this stage. 72°C is the ideal temperature for Taq polymerase. The polymerase extends the primers from 5' to 3'.
If the annealing temperature is too low, non-specific products can be generated, leading to smeared bands on the gel. If the extension time is too long, secondary products can be formed, which can contribute to smearing.
Extension is achieved by using the loosened nucleotides of each base to grow the complementary DNA strand. The end result is two double-stranded products of DNA. The temperature that is used during the extension phase is dependent on the DNA polymerase that is used.
