Yes actually that helps alots, i didn't figure in the reverse. Maybe you can help me with this one too. The question is:
The recognition site of the restriction endo is CpyCGpuG where py and pu are pyrimidines and purines. What is the expected avg distange, in nucleotide pairs, between cleavage sites in a random DNA seq.
I figured it would just be 1/(4x4x4x4x4x4) = 1/4,906
But the answer booklet says it's 1,024
What's wrong with my approach?