Final answer:
Dideoxynucleotides (ddNTPs) are used in Sanger DNA sequencing to terminate DNA replication, creating fragments of varying lengths which are then separated by size to determine the DNA sequence.
Step-by-step explanation:
The dideoxynucleotides (ddNTPs) are used to terminate the extension of DNA chains during Sanger DNA sequencing. This method, also known as the chain termination method, disrupts the DNA replication process by incorporating ddNTPs, which lack a free 3' OH group necessary for the formation of a phosphodiester bond with the next nucleotide. Therefore, no further nucleotides can be added, resulting in various lengths of DNA fragments.
An electropherogram generated by a laser scanner reads out the DNA sequence, with each fragment's length corresponding to the position of the ddNTP incorporation reflecting the sequence of the original DNA strand.
DNA sequencing via this method provides an efficient way to determine the order of nucleotides in a DNA molecule, facilitating insights into genetics and molecular biology.