Difference Between Exon and Cistron

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Basic Difference Between Cistron and Exon

The nucleus of a cell is itself a universe. A vast set of information is coded in the RNA and DNA strands in the form of genes. These genes are the blueprint of an organism. The structural and functional behavior of an organism is decided by the genetic impressions. The nuclear material is formed by RNA and DNA molecules forming single and double strands respectively. The DNA strands have coding regions called as Exons. Cistrons are the smaller units present in exons that are also called genes. There is a slight difference between these two closely-related terms. Students can get easily confused with the new terms in this biology chapter. It is very important to know the exact meaning and the differences between these two terms. For this, you need to understand what is cistron and exon first and then proceed to the differences. This is where you can study the chapter first and then proceed to the tabulated difference mentioned on this concept page. The teachers of Vedantu have compiled and simplified the differences in such a way that everyone can understand them well and can script their answers in the exams.


What is the Difference Between Cistron and Exons?

As mentioned earlier, learning about DNA and its features can be very interesting but confusing too. The new terms included in the chapter can be intimidating as the meaning and concepts are very closely related. The slight differences should be highlighted so that you can understand the exact meaning of the terms. Two such terms are cistrons and exons. Let us find out the definition of both the terms and then proceed to the differences.


Cistrons are the small segments of the DNA strands. They are also called genes. These sections are responsible for triggering and coding the peptide synthesis. The coded information in these genes is used to sequence a peptide formation and result in building protein blocks. Seymour Benzer discovered what a cistron is and what are its functions. Now that you have understood the cistron meaning, let us proceed to the exons. Hence, cistrons are used to code and form polypeptide sequences during a protein synthesis process. If a DNA strand contains only one cistron, it is called monocistronic. If there is more than one cistron in the DNA strand, it is called polycistronic.


Exons are the broader coding regions present in a DNA strand. These coding sections comprise several genes or cistrons. These coding sections can also be found in the processed or mature RNA. You can say that cistrons are building blocks of exons. Every exon has information coded in it. This information is used to build protein blocks. Exons were first found by Richard Roberts. These units can either exist together or can remain separated by introns. Introns are non-coded sequences. Introns are generally removed during the formation of functional mRNA molecule. After the formation of an mRNA molecule, it is then used to translate and build protein blocks.


Why Should We Study the Differences Between Cistrons and Exons?

Now that we have studied and understood the definition of cistrons and exons, we can proceed to the differences. As we can see exons and cistrons are very closely related and are almost similar in a structural and functional way, we need to get a little deeper to understand the concept. This is where the differences between exons and cistrons tabulated properly can be used as a reference. The best way to study it first to define cistron and exon then proceed to the structural and functional differences.


The best way to achieve conceptual development and building a foundation of knowledge of this chapter is to study the differences. Comparing both the terms properly picking up the differences in a tabulated form will deliver the right format to understand and remember. It will become a lot easier to segregate both the terms structurally and functionally. In fact, the experienced teachers of Vedantu suggest how studying the difference can help you remember the main points of a term’s definition. It can be very useful when you are studying new chapters of biology in the higher classes. Once the concept is properly inculcated, you can proceed to the more advanced chapters and learn better. Learning the differences also helps you to revise the concept of cistrons and exons. You can prepare well and answer the questions easily.

FAQ (Frequently Asked Questions)

1. What is the Difference Between a Cistron and a Gene?

Answer: Cistrons are also known as genes as they are the small codes present in a DNA strand responsible for the synthesis of polypeptide and aid in protein synthesis. Both terms are the same. Gene is quite commonly used whereas cistrons are a little more technical.

2. What are Exons?

Answer: The genes together form a segment in the DNA strand. This segment is called exons. It can be concluded that the cistrons are the building blocks of exons. Exons are responsible for protein synthesis as every cistron codes the information of a polypeptide molecule. If the exon contains one cistron, it is called monocistronic. If it contains more than cistron, it is called polycistronic.

3. What are Introns?

Answer: The non-coded sections in a DNA strand that differentiates exons are called introns. The introns help in separating exons to form functional mRNA molecules for protein translation.