Question

Why does nextgen sequencing work more effectively than Sanger sequencing when working with ancient DNA samples? What features of sequences can be used to separate sequences generated from ancient samples vs modern contaminants?

Answer 1

Two popular methods of DNA sequencing are SANGER and NEXT GENERATION sequencing.Samger sequencing was developed by Frederick Sanger and was the first sequencing method.This is a control over DNA replication process.During replication nucleotides that are complementary to the parent strand are added to the new strand using enzyme polymerase.In Sanger sequencing Special nucleotides called dideoxynucleotide are added.But once this is added ,the chain gets stopped so known as chain terminating nucleotides.For example if we try to sequence a piece of DNA like ATCGATGG.If chain terminating nucleotide A is incorporated,the chain sequencing stops at A and we get two fragments A and ATCGA.From a single pice of DNA we get DNA fragments of different length with special base at one end.

In next generation sequencing are new sequencing technology.It is almost similar to Sanger technology.But with this we can sequence larger piece of DNA or even whole genome.Many reaction can be read simultaneously.

Nextgen sequencing is more effective than Sanger because Sanger sequences only one fragment at a time while Nextgen can sequence thousands of fragments simultaneously.To sequence a whole genome nextgen is cost effective than Sanger.Sanger can sequence only short DNA pieces with 100 to 300 base pairs while nextgen can sequence large DNA pieces with 300 to 1000 base pairs.