S-phase (
synthesis phase) is the part of the
cell cycle in which
DNA is
replicated, occurring between
G1 phase and
G2 phase. Precise and accurate
DNA replication is necessary to prevent genetic abnormalities which often lead to cell death or disease. Due to the importance, the regulatory pathways that govern this event in eukaryotes are highly conserved. This conservation makes the study of S-phase in model organisms such as
Xenopus laevis embryos and
budding yeast relevant to higher organisms.