Birgid Schlindwein's
Hypermedia Glossary Of Genetic Terms
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Birgid Schlindwein'sHypermedia Glossary Of Genetic TermsSearch Results |
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| Intron | The DNA base sequence interrupting the protein-coding sequences of a gene; intron sequences are transcribed into RNA but are cut out of the message before it is translated into protein. Introns may contain sequences involved in regulating expression of a gene. Compare exon. |
| Base sequence | The order of nucleotide bases in a DNA molecule. Length is usually defined as the number of base pairs. Cf. sequence, DNA sequence. |
| Protein | A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene coding for the protein. Proteins are required for the structure, function, and regulation of the bodys cells, tissues, and organs, and each protein has unique functions. Examples are hormones, enzymes, and antibodies. |
| Gene | The term coined by Johannsen (1909) for the fundamental physical and functional unit of heredity. The word gene was derived from De Vries' term pangen, itself a derivative of the word pangenesis which Darwin (1868) had coined. A gene is an ordered sequence of nucleotides located in a particular position (locus) on a particular chromosome that encodes a specific functional product (the gene product, i.e. a protein or RNA molecule). It includes regions involved in regulation of expression and regions that code for a specific functional product. See gene expression, allele. |
| Transcription | The synthesis of an RNA copy from a sequence of DNA (a gene); the first step in gene expression. Compare translation. |
| 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. |
| Translation | The process in which the genetic code carried by mRNA directs the synthesis of proteins from amino acids. The mRNA base sequence is translated into sequence of amino acids in a peptide or protein. Occurs on ribosomes. (Cf. transcription). |
| Gene expression | The process by which a gene's coded information is converted into the structures present and operating in the cell. Expressed genes include those that are transcribed into mRNA and then translated into protein and those that are transcribed into RNA but not translated into protein (e.g., transfer and ribosomal RNAs). The degree of expression is called expressivity. |
| Exon | The protein-coding DNA sequence of a gene. Compare intron. |