What is the characteristic of the melt allele in classical PCR?

The characteristic of the melt allele in classical PCR is that it measures specific RT-PCR products across temperatures. This process is integral during the analysis of the products generated by the PCR. By analyzing the melting temperature (Tm), researchers can determine the specificity of the amplified DNA. As temperature increases, double-stranded DNA molecules will denature or "melt" into single strands at a specific temperature that is influenced by the GC content and the length of the DNA fragment. This allows for the differentiation between specific and nonspecific products, making it a vital aspect of confirming the accuracy of the PCR results.

In contrast, the other options do not accurately describe the characteristics of melt analysis. The notion that it occurs solely after PCR completion (the first option) overlooks the role of melt analysis during the PCR amplification process itself. While it is true that melt analysis is often performed after amplification is complete, the measure of specific RT-PCR products across temperatures can actually provide crucial information regarding the nature of the amplification throughout the PCR cycle.

Furthermore, the option regarding the use of external probes (the third option) does not align with the nature of melt analysis, which typically involves monitoring the melting behavior of the PCR products rather than relying on external probes for detection. Lastly, the statement