Processes and systems for preparation of nucleic acid sequencing libraries and libraries prepared using same

A method for nucleic acid processing, comprising:

• (a) providing a double-stranded nucleic acid molecule comprising at least one uracil;
• (b) in presence of barcode molecules each comprising a barcode sequence, generating a plurality of nucleic acid fragments from said double-stranded nucleic acid molecule at one or more sites corresponding to said at least one uracil, wherein said plurality of nucleic acid fragments comprise different sequences,
• wherein said barcode molecules and said double-stranded nucleic acid molecule are separate molecules;
• and
• (c) generating nucleic acid products using said plurality of nucleic acid fragments and said barcode molecules, wherein each nucleic acid product comprises (i) a sequence corresponding to a nucleic acid fragment of said plurality of nucleic acid fragments;
• and (ii) said barcode sequence or reverse complement thereof.