Ribosome, << RY buh sohm, >> is a structure in the cell that builds proteins. Proteins make up a large part of every cell. In addition, specialized proteins called enzymes help regulate many chemical reactions in the cell. Ribosomes thus play a central role in the cell’s operation. A ribosome consists of two parts, the large subunit and the small subunit. When building proteins, the subunits fit together to form a single structure. A single cell can contain from thousands to millions of ribosomes.
A protein is a complex molecule consisting of one or more long chains of amino acids. These chains are folded into three-dimensional shapes. To build a particular protein, a ribosome must assemble the amino acids that make up each chain in a specific order.
The work of the ribosome begins with a molecule called messenger RNA. RNA stands for r_ibo_n_ucleic _a_cid. Messenger RNA takes the form of a long chain. This chain serves as a _template (pattern) for assembling a particular protein. The chemical “instructions” for making the protein are encoded in the RNA chain’s sequence. These instructions have been copied from the hereditary material DNA (deoxyribonucleic acid).
In a process called translation, the messenger RNA threads between the two subunits of the ribosome. Certain sections of messenger RNA call for a particular amino acid. Another type of RNA, called transfer RNA, collects the amino acids and brings them to the ribosome attached to the messenger RNA. At each section, the ribosome gathers the appropriate amino acid and adds it to the growing chain. It then moves on to the next section, assembling the amino acids in order. After the ribosome has finished assembling the amino acid chains, the protein can fold into a shape that allows it to carry out its function in the cell.
Ribosomes are found in all kinds of living cells. Scientists can learn about the origin and evolution (development) of living things by studying changes in the ribosome. Also, many antibiotics target the ribosome, preventing harmful bacteria or fungi from producing proteins they need for growth and survival. Researchers hope that learning about the ribosome will help them to develop new and better medicines.
