Observation is essential in scientific discoveries. CRISPR was first identified in E. coli in 1987. Below is a sequence at the exact same region (downstream of the iap gene), similar to the DNA fragment sequenced in 1987. See if you could locate the CRISPR units. Mark the repeat units in red and spacers in blue.
Note: The repeat units may have a few point mutations and they are not 100% identical.
Hints: The repeat units are 28 bp long. The first 11 bp of the repeat units are identical.