Question

Differentiate between cistron, muton and recon.

Answer 1

Cistron is a section of a DNA or RNA molecule that codes for a specific polypeptide in protein synthesis, while a muton is the smallest unit in a chromosome that can be changed by mutations and the recon is the gene in real sense capable of synthesizing a polypeptide chain of an enzyme.

Complete answer:
a) Cistron: - It is the segment of DNA that contains all the information necessary for the production of a single polypeptide and includes both the coding sequences and regulatory sequences that are transcription start and stop signals. The alleles exhibit the cis-trans phenomenon.
b) Muton: - This term was coined by Benzer. It describes the smallest mutable site within a cistron. It is the smallest part of a gene that can be involved in a mutation event. It is mostly to be a single nucleotide pair. Sometimes a muton can be a normal nucleotide or it might be a radioactive element and sometimes muton might consist of 3 to 4 nucleotides.
c) Recon: - Recon is a unit of recombination. This term was coined by Seymour Benzer for the smallest recombinant unit. Recon is a part or segment of the present cistron sequence. It is a region of a gene in which there can be no crossing-over, now known to be a single nucleotide pair.

Note: The cistron is not a synonym for genes. For example for cistron, an operon is a stretch of DNA that is transcribed to create a contiguous segment of RNA but contains more than one cistron/gene. Mutation by Insertion causes Beta-thalassemia. Chromosomal deletion causes Cri-du-chat. Chromosomal translocation causes the Philadelphia chromosome. Chromosomal duplication causes a particular type of cancer.