#Id: 2530
#Unit 13. Methods in Biology
The specificity of the PCR depends crucially upon the primers. The following factors are important in choosing effective primers
Primers should be 17 to 30 nucleotides in length
A GC content of about 50% is ideal. For primers with a low GC content, it is desirable to choose a long primer to avoid a low melting
temperature.
Sequences with long runs (i.e., more than three or four) of a single nucleotide should be avoided.