Wednesday, May 13, 2015

Too Many PCR Primers!

When I order primers for teaching and research I use the Integrated DNA Technology (IDT) company.  You enter the sequence online and each primer arrives in the mail in a separate tube.  IDT primers come in a 2ml cylindrical tube with a white sticker and a blue cap (hence the color scheme for this cartoon.)

The term "22 mer" refers to a piece of single stranded DNA that is 22 nucleotides long...a typical length for a PCR primer.  So how many different DNA sequences can you make if each is 22 nucleotides long?  Each strand has 22 spots to fill and there are 4 nucleotides (A, G, C, and T).  The equation to calculate the number of unique 22 nucleotide-long DNA strands is:

422 = 17,592,186,044,416

So this lab ordered over 17 trillion different DNA strands!  (At least the guy got a free T-shirt from the company...)

No comments:

Post a Comment