Difference Between Exon and Cistron

Difference Between Exon and Cistron: Exons are the nucleotide sequences of segments of RNA and DNA which contains information coding of peptide sequence whereas Cistron is a combined form of polycistronic DNA segments which codes for a specific type of polypeptide in protein synthesis. An exon is a portion of a gene that codes for amino acids. Cistron is the genetic unit of a single polypeptide.

What is an Exon?

Exon is defined as a particular region of a gene that consists of the coding sequence for an RNA molecule. The genes which consist of both introns and exons are found in eukaryotic cells. Exons are separated by non-coding regions which are known as introns. They are the specific portions of the gene that are transcribed into mRNA and they are processed into functional RNA molecules.

What is a Cistron?

Cistron refers to the region of DNA which consists of the information necessary to produce a single polypeptide chain. It is a gene that includes all coding and non-coding sequences. It was first introduced by geneticist Seymour. They are the combined form of polycistronic. It consists of a DNA segment that codes for a polypeptide during protein synthesis.

Difference Between Exon and Cistron

Exon	Cistron
Definition
Exon is a specific region of a gene that consists of coding sequences for RNA molecule	Cistron is the entire gene that consists of all the coding and non-coding sequences.
Size
They are small in size when compared to cistrons.	Cistron consists of the entire gene which includes the introns and exons.
Consist of
They consist of many exons which are separated by introns.	Cistron consists of a single gene.
Location
They are located within the gene sequence.	They are located in the chromosome.
Functions
Their function is that they are involved in the production of functional RNA molecules.	They are the entire genetic unit which produces polypeptide chains.
Occurs
Gene expression regulation occurs in both cistron and exon.	They are involved in controlling the transcription of the whole gene.

Conclusion

Therefore, exons and cistrons are both crucial elements involved in gene expression and protein synthesis. Exons represent the coding sequences within genes and joined together to form mature mRNA molecules. On the other hand, cistrons are functional units of DNA that encode specific proteins. They encompass both the coding sequences (exons) and regulatory elements required for gene expression. While exons are specific segments within genes, cistrons represent complete genetic units responsible for the synthesis of proteins. Understanding the distinction between these two terms is essential for comprehending the intricate processes that occur within our genes and how they contribute to the diversity of proteins in living organisms.

FAQs on Exon and Cistron

Q1. Define Exon.

Ans: Exon is a particular region of a gene which consists of coding sequences for RNA molecules. Gene expression regulation occurs in both cistron and exon. They consist of many exons which are separated by introns.

Q2. Define Cistron.

Ans: Cistron is the whole gene which consists of all the coding and non-coding sequences. They are involved in controlling the transcription of the whole gene.

Q3. Write about the function of Exon and Cistron.

Ans: The function of exons is that they are involved in the production of functional RNA molecules whereas the function of cistron is that they are the entire genetic unit which produces polypeptide chains.

Q4. Write about the regulation of Exon and Cistron.

Ans: Gene expression regulation occurs in both cistron and exon whereas cistron regulation is involved in controlling the transcription of the whole gene.

Q5. State the location of the Exon and Cistron.

Ans: Exon is located within the gene sequence whereas the cistron is located in the chromosome.