Final answer:
Ribosomes are assembled in the nucleolus and consist of two subunits made of proteins and rRNA. Their main functions are protein synthesis and catalyzing peptide bond formation. Ribosomes are not membrane-bound like other organelles, and mitochondria are considered power plants due to their ATP production.
Step-by-step explanation:
Assembly and Structure of Ribosomes
Ribosomes are assembled in the nucleolus, which is a region within the nucleus of eukaryotic cells. They consist of two subunits, a large and a small one, each made up of proteins and a type of RNA known as ribosomal RNA (rRNA). These subunits come together in the cytoplasm during protein synthesis.
Functions of Ribosomes
The primary function of a ribosome is protein synthesis. It does this by binding to messenger RNA (mRNA) and translating the sequence of nitrogenous bases into a polypeptide chain, which then folds into a functional protein. Another function is catalyzing the formation of peptide bonds between amino acids, which are the building blocks of proteins.
Unlike other organelles, ribosomes are not enclosed by a membrane, which is a significant difference in their structure. Moreover, it is essential to mention that mitochondria are called the "power plants" of the cell because they produce ATP, which is the energy currency of the cell, through cellular respiration.