Toxoplasma gondii and Plasmodium berghei are obligate intracellular parasites belonging to the Apicomplexa phylum. Their successful parasitic lifestyle, culminating in pathogenesis in their respective hosts stems from complex host-parasite biological interactions. In this thesis, I investigate these parasites biology. The capacity of T. gondii to modulate host pathways and defend itself from host resistance mechanisms. The developmental relevance of both parasites ability to execute acetylation modifications on secreted proteins. In addition, I carry out an in-depth examination of T. gondii tachyzoite capabilities to replenish a growth requirement, sphingolipids through synthesis and scavenge mechanisms. CRISPR-Cas9 driven genetics, and lipidomics were used to delineate the existence of an active sphingolipids biosynthesis pathway. The biosynthesis pathway was illustrated to be crucial for development of the fast replicating T. gondii tachyzoite forms. The role of a secreted effector protein GRA60 in evasion of host cell autonomous immune responses was also uncovered