Dictionary

RNA interference The process by which the introduction of double-stranded RNA into a cell interferes with the expression of genes. Abbreviated RNAi.

RNA polymerase The enzyme that makes the very large molecule RNA, by joining together many smaller molecules, using DNA as a template.

RNAi RNA interference.

robotic surgery Surgery performed using a high-tech robotic system to perform the actual operation. Robotic surgery is most commonly used for prostate surgery, hysterectomy, heart valve and blood vessel repair, pediatric surgery, and urologic surgery.

rib One of the 12 paired arches of bone that form the skeletal structure of the chest wall (the rib cage). The ribs attach to the vertebrae of the spine in the back. The 12 pairs of ribs consist of 7 pairs of ribs that attach to the sternum in the front and are known…

rib, cervical An extra rib that arises from the seventh cervical vertebra. It is located above the normal first rib. A cervical rib is present in only about 1 in 200 people. It may cause pinching of nearby nerves or arteries, in which case it sometimes is removed surgically.

rib, floating or vertebral or fluctuating – See false rib.

rib, sternal See true rib.

ribonucleic acid A nucleic acid that is similar to DNA but contains ribose rather than deoxyribose. Abbreviated RNA. RNA, in fact, can form upon a DNA template. The several classes of RNA molecules play important roles in protein synthesis and other cell activities. See also messenger RNA; RNA, ribosomal; RNA, transfer.

ribosome A tiny structure in the cytoplasm of a cell (outside the nucleus) that functions as the protein factory for the cell.

ribozyme An RNA molecule that has enzymatic activity. See also ribonucleic acid.

rickets 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”),…