Question

gao caixia and colleagues (2024) at the chinese academy of sciences have introduced a suite of groundbreaking genome engineering technologies that dramatically expand the scale and precision of dna modification in eukaryotic cells through the cre - lox system. traditionally, this tool has been prone to reversing its own edits due to the symmetrical design of its target sites, exhibited structural complexities that complicate efforts to improve its performance, and left behind small residual sequences that compromise the accuracy of the final result. the research team developed two advanced genome engineering systems—programmable chromosome engineering (pce) and repce—that achieve high - precision dna modifications in eukaryotic cells while addressing the issues that limited its applicability.
4 mark for review
what is the main purpose of the text?
a to describe recent innovations in genome editing that overcame technical constraints on its utility.
b to propose a theoretical revision of eukaryotic chromosomal structure grounded in recent discoveries.
c to detail methodological refinements that extend the functional utility of an established genetic tool.
d to illustrate why the team designed genome engineering systems that improved upon an existing one.

Explanation:

• Option A: The text focuses on refining an existing tool (Cre - Lox) with new systems, not just describing recent innovations in genome editing in general. The emphasis is on improving an established tool, not just any recent innovations.
• Option B: The text is about genome engineering technologies (tools) and their improvements, not a theoretical revision of eukaryotic chromosomal structure.
• Option C: The text first presents the problems of the existing Cre - Lox tool (like reversing edits, structural complexities, residual sequences) and then introduces the two new genome engineering systems (PCE and RePCE) that address these issues and thus extend the utility of the genetic tool (Cre - Lox - based genome editing). This option accurately captures the main purpose of detailing how the methodological refinements (new systems) extend the functional utility of the established genetic tool (Cre - Lox system).
• Option D: The text is not mainly about illustrating why the team designed the new systems, but rather about showing how the new systems improve the existing tool and extend its utility. The focus is on the refinements and their effect on the tool's utility, not the reason for designing the systems.

Answer:

C. To detail methodological refinements that extend the functional utility of an established genetic tool.