Practice question

Nucleomorph denotes highly reduced vestigial nucleus retained in periplastidial compartment of certain secondary plastids, demonstrating former free-living eukaryotic nature of engulfed alga. Found in cryptophytes retaining red algal nucleomorph with three linear chromosomes and in chlorarachniophytes retaining green algal nucleomorph, it encodes primarily housekeeping genes, rRNAs, and some plastid-targeted proteins. Ultrastructurally located between second and third membranes of plastid envelope, nucleomorph genome is among smallest eukaryotic genomes. Its presence serves as living fossil evidence of eukaryote-eukaryote endosymbiosis and algal nuclear origin.