Final answer:
The 454 system allows massive parallel sequencing using emulsion PCR, beads, adapters, and picotiter plates. DNA fragments are attached to beads, amplified using PCR, and placed into separate wells on a picotiter plate. Each nucleotide is added one after the other, and the order of nucleotides incorporated is recorded to determine the sequence.
Step-by-step explanation:
In 454 sequencing, a DNA sample is fragmented into 400-600 base pair single-strand fragments. DNA adapters are then attached to both ends of each fragment. Each fragment is attached to a bead and amplified using PCR, creating beads with many copies of that DNA fragment. These beads are placed into separate wells on a picotiter plate containing sequencing enzymes. Each of the four nucleotides is added one after the other, and when incorporated, pyrophosphate is released, emitting a small flash of light that is recorded by a detector. This allows the order of nucleotides incorporated to be determined, resulting in the sequencing of the DNA sample.