Unlock Your Genetic Genius: Ace the 2026 Leaving Cert Biology Test!

Some organelles keep their own genetic material separate from the nuclear genome, reflecting their bacterial ancestry. Mitochondria carry mitochondrial DNA with a small set of genes essential for energy production, and chloroplasts carry chloroplast DNA with genes for photosynthesis. These organelles replicate on their own and have their own ribosomes, supporting that independent genetic system. The nucleus holds the vast majority of the cell’s DNA, while other organelles like Golgi, lysosomes, peroxisomes, and the rough ER do not contain separate genomes. So the organelles that truly have their own genetic material apart from the nucleus are mitochondria and chloroplasts.