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Ribonucleic acid.

(1) is a molecule present in the cells of all living beings and is essential for the synthesis of proteins . There are different types of RNA, including messenger RNA (mRNA), and transfer RNA (tRNA). mRNA transmits information encoded in DNA, while tRNA uses this information to manufacture proteins.

(2) Science: molecular biology) A nucleic acid found in all living cells. Plays a role in transferring information from dNA to the protein-forming system of the cell. (biochemistry) a long linear polymer of nucleotides found in the nucleus but mainly in the cytoplasm of a cell where it is associated with microsomes; it transmits genetic information from dna to the cytoplasm and controls certain chemical processes in the cell; ribonucleic acid is the genetic material of some viruses.A nucleic acid similar to that of dna, thought the deoxyribose acid is replaced with ribose sugar and all thymine bases are replaced with uracil. Rna is a vital component of protein synthesis as it is able to read the genetic blueprint found in dna to make.

RNA (RiboNucleic Acid) molecules have only one strand, compared to DNA , which has two strands. Like DNA, they contain the bases adenine, guanine, and cytosine, but thymine (T) is replaced by uracil (U). mRNA is synthesised by making a copy of one of the two DNA strands of a gene (except using U in place of T); this process is called, “DNA transcription.” During protein synthesis, the anti codon of tRNA (sequence of 3 bases) places itself opposite the corresponding codon of mRNA. Using this process and the genetic code , the tRNA contributes its amino acid to a protein chain under construction. There is a specific tRNA for each of the 20 types of amino acids that form proteins.

Ribonucleic acid (RNA)

A chemical found in the nucleus and cytoplasm of cells; it plays an important role in protein synthesis and other chemical activities of the cell. The structure of RNA is similar to that of DNA. There are several classes of RNA molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each serving a different purpose.

Complementary RNA (cRNA)

Viral RNA that is transcribed from negative-sense RNA and serves as a template for protein synthesis.

Heterogeneous nuclear RNA (hnRNA)

A diverse group of long primary transcripts formed in the eukaryotic nucleus, many of which will be processed to mRNA molecules by splicing.

Messenger RNA (mRNA)

Messenger RNA (mRNA) is a type of RNA that reflects the exact nucleoside sequence of the genetically active DNA. mRNA carries the “message” of the DNA to the cytoplasm of cells where protein is made in amino acid sequences specified by the mRNA.

MicroRNA (miRNA)

Small RNAs containing 21 to 33 nucleotides that associated with multiple proteins in a RNA-induced silencing complex (RISC) that repress transcription of specific target mRNA by hybridizing to its 3' untranslated region.

Negative-sense RNA

Viral RNA with a base sequence complementary to that of mRNA; during replication it serves as a template for the transcription of viral complementary RNA.

Positive-sense RNA

Viral RNA with the same base sequence as mRNA; during replication it functions as mRNA, serving as a template for protein synthesis.

Ribosomal RNA (rRNA)

A class of RNA found in the ribosomes of cells. Ribosomal RNA functions as a nonspecific site for making polypeptides.

RNA interference (RNAi)

The functional inactivation of specific genes by experimental introduction of a corresponding double stranded RNA, which induces degradation of the complementary single-stranded mRNA encoded by the gene but not that of mRNAs with different sequences.

RNA primer

A sequence of about 10 nucleotides long copied from DNA by RNA primase and required for the priming of the synthesis of each Okazaki fragment during DNA replication.

RNA viruses

viruses distinguished by having a ribonucleic acid genome, usually as a single strand which may be positive or negative sense, a single molecule or a segmented; in at least two families the genome is a double-strand segmented form.

secondary structure RNA

Folding of single-stranded RNA molecules which arises from intramolecular base pairing.

small cytoplasmic RNA (scRNA)

Small (7S; 129 nucleotides) RNA molecules found in the cytosol and rough endoplasmic reticulum associated with proteins that are involved in specific selection and transport of other proteins.

Small nuclear RNA (snRNA)

A class of eukaryotic small RNA molecules found in the nucleus, usually as ribonucleoproteins, and apparently involved in processing heterogeneous nuclear RNA.

Transfer RNA (tRNA)

20 or more varieties of small RNA molecules functioning in translation; each variety carries a specific amino acid to a site specified by an RNA codon, binding to amino acid, ribosome, and to the codon via an anticodon region.


Sources: Biology OnLine; Dorland's Medical Dictionary for Health Consumers; Saunders Comprehensive Veterinary Dictionary; MedicineNet

glossary/rna.txt · Last modified: 2012/10/16 14:40 (external edit)