Cistron

A segment of DNA that encodes a single polypeptide chain or protein.

A cistron is a segment of DNA that encodes a single polypeptide chain or protein. The term "cistron" is synonymous with "gene" in the context of molecular biology.

Structure and Function

A cistron is defined by its ability to produce a functional product, typically a protein, through the processes of transcription and translation. Each cistron contains a sequence of nucleotides that includes a promoter, a coding sequence, and a terminator.

Promoter

The promoter is a region of DNA that initiates transcription of a particular gene. Promoters are located near the transcription start sites of genes and can be about 100–1000 base pairs long.

Coding Sequence

The coding sequence of a cistron is the portion of a gene's DNA or RNA that codes for protein. The coding sequence is composed of exons and is translated into a sequence of amino acids.

Terminator

The terminator is a section of nucleic acid sequence that marks the end of a gene or operon in genomic DNA during transcription.

Cistron vs. Gene

While the term "cistron" is often used interchangeably with "gene," it specifically refers to the functional unit of heredity that encodes a single polypeptide. In contrast, a gene may include multiple cistrons, especially in eukaryotic organisms where genes can be split into multiple exons and introns.

Historical Context

The concept of the cistron was introduced by Seymour Benzer in the 1950s as a way to describe the functional units of genetic material. Benzer's work on the rII locus of bacteriophage T4 helped to elucidate the fine structure of genes.

See Also

• Gene
• Operon
• Transcription (genetics)
• Translation (biology)
• Protein synthesis

External Links

• Cistron on WikiMD