A molecular component of a ribosome, the cell’s essential protein factory. Ribosomal RNA (rRNA) fabricates polypeptides (assemblies of amino acids that make up proteins).
A tiny particulate structure located in the cytoplasm of the cell (outside the nucleus), the ribosome is composed of two subunits, one larger than the other. Both subunits were believed to contain both rRNA and protein but this is not the full story. Molecular maps of the ribosome have revealed startling details about its structure that boost support for an “RNA world” as the model for the origin of life on Earth. Although the ribosome consists of both ribosomal RNA (rRNA) and protein, the “active site” on the large unit of the ribosome — the site of the chemical reaction that changes genetic information into the beginnings of a protein — contains only rRNA. This suggests that the ribosome is actually a ribozyme, an RNA molecule that can catalyze its chemical reactions. RNA’s starring role in the ribosome may therefore support the idea that life on Earth began with RNA.
A tiny structure in the cytoplasm of a cell (outside the nucleus) that functions as the protein factory for the cell.
An RNA molecule that can catalyze its own chemical reactions.
- Rice genome
The first commercially important plant to have its genome sequenced. This feat, completed early in 2001, is particularly important because rice is a staple food for a large portion of the population of the world. With the rice sequence, genes can be located to improve yields and make rice more nutritious. Rice was the second […]
A potent protein toxin made from the waste left over from processing castor beans. The castor plant, which is called Ricinus communis, is found throughout the world. Ricin is fairly easy to extract. Worldwide a million tons of castor beans are processed annually in the production of castor oil. The waste mash from this process […]
A disease of infants and children that disturbs normal bone formation (ossification), leading to failure to mineralize bone. Rickets softens bone, producing osteomalacia, and permits marked bending and distortion of bones. Other features of rickets include softness of the infant’s skull (craniotabes), enlargement of the front end of the ribs (creating the ‘rachitic rosary’), thickening […]