Which method utilizes chemical modification of DNA followed by cleavage at specific bases?

The method that utilizes chemical modification of DNA followed by cleavage at specific bases is indeed Ma'am-Gilbert sequencing. This technique involves the modification of DNA strands using specific chemicals that attach to certain bases, allowing for the selective cleavage of those modified bases. After cleavage, the resulting fragments can be analyzed to determine the sequence of the DNA.

Ma'am-Gilbert sequencing is a historic method of DNA sequencing that relies on this chemical treatment, providing a way to identify the order of nucleotides in the DNA by creating specific patterns of cuts that can then be read to infer the sequence.

Other techniques mentioned are distinct in their methods and purposes. Next generation sequencing involves massively parallel sequencing techniques that are more advanced and digital-based, while mass spectrometry is primarily used for measuring the mass of molecules rather than sequencing DNA. The polymerase chain reaction is a technique used to amplify DNA but does not involve specific cleavage of modified bases. Thus, the unique method of chemical modification followed by cleavage is characteristic of Ma'am-Gilbert sequencing.