Final answer:
Membrane-enclosed components of cells that perform specialized functions are organelles such as the nucleus, mitochondria, and Golgi apparatus. Ribosomes, while essential, are not membrane-bound and not classified as such organelles.
Step-by-step explanation:
Membrane-enclosed components of cells that carry out specialized functions are known as organelles. These organelles include the nucleus, mitochondria, endoplasmic reticulum, and Golgi apparatus. While ribosomes are involved in protein synthesis and are essential to cell function, they are not membrane-bound and are therefore not classified in the same category as the other organelles listed here, which are all enclosed by membranes. The mitochondria produce energy through cellular respiration, the nucleus contains genetic information, and the Golgi apparatus is involved in modifying, tagging, and packaging proteins for transport.