Final answer:
Ribosomes are vital cell organelles made of rRNA and proteins responsible for translating mRNA into proteins. They consist of two units and can be free in the cytoplasm or bound to the endoplasmic reticulum. Their enzymatic activity plays a crucial part in the assembly of proteins, an essential process for all living cells.
Step-by-step explanation:
Ribosomes and Protein Synthesis
Ribosomes are essential cellular structures responsible for protein synthesis. Composed of protein and rRNA, ribosomes are found either as clusters known as polyribosomes or as single units within the cell's cytoplasm. They may also be attached to the cytoplasmic side of the plasma membrane or the endoplasmic reticulum, as well as the nuclear envelope. Ribosomes consist of two subunits, a large and a small one, which come together during the process of protein synthesis.
Protein synthesis involves interactions between mRNA, ribosomes, tRNAs, and enzymatic factors. The sequence of nitrogenous bases in mRNA, which is transcribed from DNA in the nucleus, is translated by ribosomes into a specific order of amino acids, forming proteins. This translation process is critical for cell function and involves three phases: initiation, elongation, and termination.
Ribosomes have been classified as ribozymes due to the catalytic activity of rRNA, particularly the peptidyl transferase function, which forms peptide bonds between amino acids. Active sites within ribosomes, referred to as E, P, and A sites, are pivotal for their catalytic activity. The entirety of this process is not only fundamental for protein synthesis but also for the overall functionality of biological cells.