Reading a Long DNA Sequence

To read a very long DNA molecule requires a time-consuming “walk” along the length of the DNA. Sequence from a partial “read” is used to prime the next section of sequence, resulting in a series of overlapping reads.

Three overlapping purple lines, each with a pink primer on the left side. The top line is labeled Sequence read by Sanger sequencing. An arrow points from the end of the top sequence to the Next primer on the Next sequence. Again, an arrow points from the end of the second sequence to the Next primer on Next sequence.