Features and Genes

A feature is anything that can be mapped onto a strand of DNA, and is defined by its start and stop location.

Feature is a catch-all, general term, heavily used in bioinformatics and genomics. Its usage and meaning is similar to that of the term more familiar to biologists, locus. There are many different types of features.

A gene is a feature. There are several types of genes. The term gene is most commonly used to describe loci that encode proteins, and may be referred to as a protein encoding gene (PEG), protein coding sequence (CDS), or open reading frame (ORF, although not all ORFs are expressed genes). Alternatively, genes may encode structural or functional RNAs, such as rRNA, tRNA, and sRNA. Protein encoding genes are commmonly described as structural or regulatory. Structural genes encode enzymes and structural proteins. Regulatory genes encode proteins that function to regulate the expression of other genes, often by binding specifically to short sequences of the DNA, called regulatory elements.

Regulatory elements are features that are much smaller than genes. There are several types of regulatory elements, such as promoters, operators, ribosome binding sites (RBS), terminators, or other protein binding sites (PBS).

There are also several features defined as sets of smaller features. Pathogenicity islands (PI) and prophages (PP) are features that include many genes. Operons include genes and regulatory elements.

In conclusion, while genes are features, not all features are genes. These terms are not synonymous. Features may be as small as a single nucleotide polymorphism (SNP) or as large as a prophage or superintegron.

Topic revision: r6 - 16 Jan 2009 - 15:05:36 - TWiki Guest
 
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