In Day 12 of 12 days of Biopython, I am going to show you how to filter sequence data coming from FASTQ files by their PHRED quality scores using the Biopython SeqIO module. Chapters: 0:00 Intro 0:42 Get sample FASTQ file 0:55 Parsing FASTQ file to get the number of sequences 1:19 Accessing phred quality scores using .letter_annotations 1:45 Filtering out sequences whose phred quality score is below some threshold 2:48 Outro You can link to the Github code here. My videos are aimed at everyone interested in Computer Science applications in biology. The mission is to simplify Bioinformatics concepts, one video at a time! Follow me on Twitter.