Sister chromatids are replicated and held together by cohesion machinery until anaphase, ensuring each daughter cell receives a full chromosome set. This thesis tests whether proteins involved in DNA replication and repair, including PCNA, Ctf7p, RFC subunits, Rad24p and Elg1p, physically interact with and have a role in establishing sister chromatid cohesion. It was found that PCNA and Elg1p specifically interact with Ctf7p, though no cohesion defect was found for a pol30 allele, suggesting these proteins may be involved in cohesion but their exact roles require further investigation.