A granule of protein and RNA, synthesized in the nucleolus and found in the cytoplasm of cells. Ribosomes are the main sites of protein synthesis. Messenger RNA attaches to them and there receives molecules of transfer RNA bearing amino acids.
The molecular “machines” within cells that coordinate the interplay of tRNAs, mRNA, and proteins in the complex process of protein synthesis (manufacture). RNA constitutes nearly two-thirds of the mass of these large (mega-Dalton) molecular assemblies. The formation of a ribosome (in a cell) is largely a self-assembly process, because all of the information needed for the correct assembly of this structure is contained in the primary structure of its (molecular) components. The assembly process is ordered and proceeds in stages. Many ribosomes (in a given cell) can simultaneously translate an mRNA molecule. The structure, consisting of a group of ribosomes bound to an mRNA molecule that is actively synthesizing protein, is called a polyribosome or a polysome. The ribosomes in this (polysome) unit operate independently of each other, each synthesizing a complete polypeptide (protein) chain.
The site of protein synthesis within a cell. Protein synthesis can take place only when all amino acids are available within the cell.
A tiny particle in a cell, containing RNA and protein, where protein is synthesised.
The organelle of the cell where protein synthesis occurs.
Deposits of nucleic acid (RNA and DNA) scattered throughout the cytoplasm of the bacterial cell.
Organelle composed of ribonucleic acid (RNA) and found in the cytoplasm of cells, where it serves as the site of protein synthesis.
A particle, consisting of RNA and protein, that occurs in cells and is the site of protein synthesis in the cell. Ribosomes are either attached to the endoplasmic reticulum or free in the cytoplasm as polysomes.
Granules either found free within the cell, or attached to a reticular network within the cell’s endoplasm (the inner part of a cell’s cytoplasm). Consisting of approximately 65 per cent RNA and 35 per cent protein, they are the sites where protein is made.
A cell organelle made of ribosomal RNA and protein. Ribosomes may exist singly, in clusters called polyribosomes, or on the surface of rough endoplasmic reticulum. In protein synthesis, they are the site of messenger RNA attachment and amino acid assembly in the sequence ordered by the genetic code carried by mRNA.