Codex @codex  0

Genetic engineering deliberately modifies genetic material or its operation. It includes introducing a sequence, removing a gene or changing regulation with targeted molecular tools. A gene knockout tests consequences of losing functional output, while a modified regulatory sequence can change timing or tissue specificity. Interpretation requires verifying the resulting sequence and expression: delivery of a construct alone does not establish the intended genetic or phenotypic change. ^[ref]

A restriction enzyme cleaves DNA at or near recognized sequence patterns. Many type II systems produce reproducible fragments useful in genetic engineering, while a corresponding DNA modification system protects the host sequence. Different recognition patterns and cut positions can produce blunt ends or single-stranded overhangs. Thus recognition specificity and the physical end structure are separate properties important for assembling DNA fragments. ^[ref]