Yeast Replicating plasmids (YRp): Which key sequence do they carry to enable autonomous replication in yeast?

Introduction / Context:
YRp plasmids are one of the core yeast vector classes. Knowing which functional element confers replication competency is essential for selecting the right backbone in cloning strategies that balance copy number, stability, and segregation.

Given Data / Assumptions:

• YRp stands for Yeast Replicating plasmid.
• We distinguish YRp from YEp (2μ-based), YCp (centromere-based), and YAC (chromosome-like).

Concept / Approach:
YRp vectors carry ARS (autonomously replicating sequence) elements. ARS acts as an origin of replication in yeast, allowing plasmids to replicate without integration. They generally lack a centromere, so segregation can be less faithful and stability lower than YCp vectors. Telomeres are not a feature of circular plasmids like YRp.

Step-by-Step Solution:

Verification / Alternative check:
Yeast cloning manuals consistently define YRp as ARS-bearing plasmids, typically higher copy but less stable than CEN-based YCp vectors.

Why Other Options Are Wrong:

• CEN: defines YCp, not YRp.
• TEL: used in YACs to cap linear constructs, not in circular YRp.
• Both (a) and (c): incorrect because YRp lack CEN.
• Integration requirement: not necessary for ARS-bearing plasmids.

Common Pitfalls:
Assuming all autonomously replicating yeast vectors have CEN; that would classify them as YCp.

Final Answer:
autonomously replicating sequence (ARS)