PCR protocol fundamentals—hands-on operation guide

critical

No Band Due to Incorrect Component Concentrations

No visible band or very faint band on gel despite proper thermal cycling parameters. The reaction components may be at suboptimal or inhibitory concentrations.

💡 5 · ✓ 5

critical

No Band or Faint Band Due to Incorrect Component Concentrations

PCR amplification fails or produces very weak bands. Thermal cycling parameters appear correct, but reaction components may be improperly balanced or missing.

💡 6 · ✓ 6

critical

Complete Absence of PCR Product

No bands visible on agarose gel after PCR amplification, indicating complete reaction failure.

💡 6 · ✓ 6

severe

No Band or Faint Band Due to Reagent Concentration Issues

Gel shows no amplification product or very weak bands despite correct thermal cycling parameters, indicating problems with reaction component concentrations.

💡 6 · ✓ 6

severe

Low or No Amplification Due to Template Issues

PCR yields little to no product visible on gel electrophoresis. Expected band is absent or extremely faint despite using standard reaction conditions.

💡 6 · ✓ 6

severe

Sample Fails to Amplify Despite Positive Control Success

Positive control amplifies successfully but test sample known to contain target shows no amplification; undiluted template fails while dilutions may show improved amplification

💡 3 · ✓ 5

severe

Sequence Errors in PCR Product

Sequencing of the PCR product reveals mutations, insertions, deletions, or other sequence variations compared to the original template DNA.

💡 6 · ✓ 6

severe

No Product Due to Suboptimal Cycling Parameters

No amplification product visible despite proper template and reagents, suggesting thermal cycling conditions are inappropriate.

💡 4 · ✓ 4

moderate

Smeared Bands Due to Template Quality or Concentration Issues

Gel displays smeared bands suggesting degraded products or heterogeneous amplification. Template-related issues such as degradation, contamination, or excessive concentration are suspected.

💡 6 · ✓ 6

moderate

PCR污染和携带污染

Unexpected products appear in negative controls or multiple samples show identical non-specific bands, indicating contamination from previous amplifications or environmental sources.

💡 4 · ✓ 7

moderate

Excessive DNA Smearing on Gel

Amplified DNA appears as broad smear rather than discrete bands, indicating degradation or over-amplification artifacts.

💡 8 · ✓ 8

moderate

Amplification Failure from Suboptimal Cycling Parameters

No product or very weak bands despite proper template and primer quality. Reaction components appear functional in other assays.

💡 4 · ✓ 4

moderate

JumpStart Taq ReadyMix Underperforming Due to Incorrect Hot Start Protocol

JumpStart Taq ReadyMix does not work as well as similar products from different suppliers; amplification is weak or absent despite correct assay design

💡 3 · ✓ 3