The basic structural unit of chromatin is the nucleosome composed of ~147 base pairs of DNA wrapped around an octamer of histone proteins. Post-translational modifications such as histone acetylation or the substitution of histone variants in place of core histones have been implicated in various chromatin related processes. There are two distinct chromatin assembly pathways. Replication-dependent mediated by CAF-1 (H3-H4) and replication-independent mediated by HIRA (H3.3-H4). Miss-regulation of chromatin assembly patterns result in the onset of many disease states such as cancer. Tetrahymena thermophila is a useful model for understanding basic questions in chromatin biology due to the segregation of transcriptionally active and silent chromatin into two distinct nuclei. To better characterize replication-dependent and independent chromatin assembly pathways in T. thermophila, I have engineered somatic knockouts (HIRA, CAC2, UBN1 and UBN2) and initiated the functional analysis of these chromatin assembly genes mediated in growth and development. The absence of CAC2 results in larger macronuclei and speculated to be a result of reduced histone H3-H4 deposition onto chromatin during growth.