Properties of yeast integrative plasmids (YIp) — mechanism of transformation Which statement correctly describes YIp vectors and how they establish themselves in Saccharomyces cerevisiae?

Introduction / Context:
Yeast cloning tools come in several flavors—integrative (YIp), replicative (YRp), episomal (YEp), centromeric (YCp), and artificial chromosomes (YAC). Understanding each class is crucial for choosing the right vector for stability versus copy number.

Given Data / Assumptions:

• YIp lacks ARS and 2μm replication elements.
• Integration relies on homologous sequences (for example, selectable markers or gene fragments) to recombine into the yeast genome.
• Stable maintenance follows chromosomal segregation.

Concept / Approach:

Because YIp vectors do not carry yeast replication origins, they cannot persist as free plasmids. Instead, linearized or appropriately targeted circular YIp constructs integrate into chromosomal loci via single or double crossover events, conferring high genetic stability.

Step-by-Step Solution:

Verification / Alternative check:

Yeast transformation protocols for gene replacement employ YIp-based constructs to knock in or disrupt genes, demonstrating their integrative mechanism.

Why Other Options Are Wrong:

High-copy episomal maintenance (option b) describes YEp; ARS-based replication (option c) describes YRp; centromere/telomere artificial chromosome behavior (option d) describes YAC; option e is incorrect since YIp can transform yeast via recombination.

Common Pitfalls:

Assuming all plasmids carry ARS; YIp specifically does not, which is the defining feature.

Final Answer:

They integrate into the genome by homologous recombination (crossing over) rather than autonomous replication