I want to extract some base pairs from a FASTA file. There is a given sequence, say marker sequence. Every time this marker sequence occurs in the FASTA file, I want to extract n base pairs to the left of it (before it). Is it possible to do so using biopython? If so, please tell.
PS - I know it seems quite simple. But I am very new to python. And I have to do this using biopython only. So finding it very difficult to understand from the cookbook.