Final answer:
In Sanger sequencing, DNA chains are detected using dye-labeled dideoxynucleotides. These molecules terminate DNA replication at specific points and are read by a laser scanner after separation by electrophoresis, resulting in a sequence electropherogram.
Step-by-step explanation:
In the context of Sanger sequencing, which is a method of DNA sequencing developed by Frederick Sanger, the detection of DNA chains is accomplished using dye-labeled dideoxynucleotides. These specialized molecules are used in the chain termination method to generate a mixture of DNA fragments that are terminated at each successive nucleotide base. During electrophoresis, DNA fragments are separated based on size. After separation, the DNA fragments pass by a laser that excites the dye labels, allowing a laser scanner to detect the emitted fluorescence and generate an electropherogram. This electropherogram provides a readout of the DNA sequence.
By understanding the principles of chain termination and detection with labeled ddNTPs, it becomes evident that capillary gel electrophoresis and dye-labeled dideoxynucleotides are key components used for the detection of DNA fragments in Sanger sequencing.