Eukaryotic cells are characterised by the presence of membrane-bound organelles, each serving specific functions. The nucleus, for instance, is the control centre of the cell, storing DNA and regulating gene expression. Mitochondria, often dubbed the powerhouses of the cell, produce ATP, the primary energy currency, through cellular respiration. Meanwhile, ribosomes are the sites of protein synthesis, the endoplasmic reticulum aids in the production of proteins and lipids, and the Golgi apparatus modifies, sorts, and packages these proteins for transport.