Deletion of which domain of ARS would give the least replication rate in eukaryotes

The ARS (Autonomously Replicating Sequence) is a DNA sequence that allows for the replication of DNA in yeast and is analogous to replication origins in other eukaryotes. ARS elements contain specific DNA sequences that are recognized by replication initiation proteins and serve as sites for the assembly of the pre-replicative complex (pre-RC), which initiates DNA replication.

Deletion of the B3 domain within an ARS element would likely result in the least replication rate in eukaryotes. The B3 domain, also known as the B2/B3 element, is a conserved region within ARS elements that is critical for the initiation of DNA replication. It contains binding sites for key replication initiation proteins, such as the Origin Recognition Complex (ORC) and the Minichromosome Maintenance (MCM) complex, which are essential for the assembly of the pre-RC and the initiation of DNA replication.

Without the B3 domain, the ARS element would be unable to efficiently recruit the necessary replication initiation proteins, leading to a decreased rate of DNA replication. While deletion of other domains within the ARS element may also impair replication, deletion of the B3 domain would likely have the most significant impact on replication rate due to its central role in the initiation of DNA replication.