Final answer:
The number of bases of sequence generated for each DNA fragment after the first chip scan varies with sequencing technology: hundreds for Sanger sequencing to up to 600 base pairs with certain next generation sequencing methods.
Step-by-step explanation:
After scanning the chip for the first time, each DNA fragment will have generated a sequence that is determined by the method used. For example, in the Sanger dideoxy sequencing method, the length of each sequence will correspond to the point at which a fluorescent dideoxynucleotide was incorporated, terminating the chain. This results in various fragment lengths which can then be translated into a sequence.
With more modern next generation sequencing (NGS) technologies, the number of bases sequenced in each fragment can range widely, from 25 to 600 base pairs, allowing for the rapid generation of millions of short DNA sequences. For instance, with 454 sequencing, each DNA fragment, being in the range of 400-600 base pairs, is sequenced by adding nucleotides sequentially and detecting the release of pyrophosphate with each incorporation, which emits a detectable light signal.
The final count of generated bases will depend on the specific protocol and technology used, but these are typically in the hundreds for traditional Sanger sequencing and can reach up to 600 for some NGS techniques.