An abstraction used in the description and quantification of heredity
?--a discrete unit of inheritance
?.
A gene refers to a sequence of DNA that codes for a particular protein (made up of a string of amino acids). Active genes generally are delimited by a 'start' and a 'stop' codon (a short DNA sequence which is recognized by the cell as a point either to start or to stop translation of the gene).
Much of the chromosome in many organisms contains DNA of no apparent function (sometimes referred to as 'junk DNA'). In many cases, this probably represents genes which have become inactive due to DNA rearrangement or mutation at the delimiting codon sites. An interesting field of exploration is the attempt to 're-activate' such "lost" genes, producing such things as real hen's teeth, for instance.
Typical numbers of genes in an organism:
- See: genetics, gene therapy