Question

What is cistron?

Answer 1

Hint: It is present in the DNA of all prokaryotic and eukaryotic cells.

Complete answer:
Cistron is a DNA segment equivalent to a gene. It is the smallest unit of genetic material which codes for a single polypeptide and functions as a transmitter of genetic information. Thus saying a gene might consist more than one cistron.

Taking the following example, say a mutation takes place at a chromosome position A which is responsible for a change in the recessive trait in a diploid organism. We say that the mutation is recessive unless both chromosomes of a pair have the mutation the trait will not be expressed. Now suppose a mutation takes place at another position B and it is responsible for the same recessive trait then the positions A and B are said to be within the same cistron.

Note:
- Seymour Benzer was an American molecular biologist who developed a method used to determine the detailed structure of viral genes and coined the term cistron to denote functional subunits of genes.
- Exons are the nucleotide sequences in DNA and RNA that are completely conserved in the creation of mature RNA during transcription
- Introns are the nucleotide sequences in DNA and RNA that do not code for proteins, and are thus removed during maturation of mRNA by RNA splicing.
- The main difference between cistrons and exons is that exons are the coding regions of DNA, and one exon may have several cistrons.