7 Major Difference Between Introns And Exons (With Comparison Chart)

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What Are Introns?

 An intron is any nucleotide sequence within a gene that is removed by RNA splicing during maturation of the final RNA product.  Introns are found in the genes of most organisms and many viruses and can be located in a wide range of genes including those that generate proteins, ribosomal RNA (rRNA) and transfer RNA. When proteins are generated from intron-containing genes,  RNA splicing takes place as part of the RNA processing pathway which follows transcription and precedes translation.

What You Need To know About Introns

  • Introns also referred to as the interveningsequence, are the non-coding region of the nucleotide sequence and are present between the two exons.
  • Introns belong to the non-coding DNA.
  • Introns are very much common in the genome of higher vertebrates such as human beings, mammals, amphibians, fish and mice but unlikely to be seen in the genome of certain varieties of eukaryotic micro-organism.
  • Introns are less conserved. What this means is that they change their sequence very often over time.
  • Intons can be termed as DNA bases that are found between Exons
  • Because Introns are non-coding part, they remain in the nucleus only after the splicing out from the mRNA primary transcript during mRNA processing inside the nucleus.
  • Introns are present in DNA and in the primary transcript or pre-mRNA only.

What Are Exons?

An exon is any part of a gene that will encode a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. Exons are made up of stretches of DNA that will ultimately be translated into amino acids and proteins. In the DNA of eukaryotic organisms, exons can be together in a continuous gene or separated by introns in discontinuous gene. When the gene is transcribed into pre-mRNA the transcript contains both introns and exons.

What You Need To Know About Exons

  • Exons also referred to as expressed sequence are the coding region of the nucleotide sequence and are only responsible for the synthesis of proteins in the cytoplasm.
  • Exons belong to the coding DNA.
  • Exons are found in both prokaryotes and in eukaryotes.
  • Exons on the other hand, are very highly conserved sequence.
  • Exons can be termed as DNA bases which are translated into mRNA.
  • Exons are coding part, they move to the cytoplasm for protein synthesis after the production of the mature mRNA.
  • Exons mark their presence in the DNA as well as mature mRNA.

Also Read: Difference Between Template And Coding Strand

The Difference Between Introns And Exons In Tabular Form

Basis Of Comparison Introns Exons
What are they? Is the non-coding region of the nucleotide sequence and are present between the two exons. Are the coding region of the nucleotide sequence and are only responsible for the synthesis of proteins in the cytoplasm
Where they belong on DNA Belong to the non-coding DNA. Belong to the coding DNA.
Common Presence Commonly found in prokaryotes. Found in both prokaryotes and in eukaryotes.
Change of Sequence Less conserved. What this means is that they change their sequence very often over time. Very highly conserved sequence.
Location as DNA Bases Can be termed as DNA bases that are found between Exons Can be termed as DNA bases which are translated into mRNA.  
Movement in the Nucleus They remain in the nucleus only after the splicing out from the mRNA primary transcript during mRNA processing inside the nucleus. They move to the cytoplasm for protein synthesis after the production of the mature mRNA.
Presence in the Genome Present in DNA and in the primary transcript or pre-mRNA only. Mark their presence in the DNA as well as mature mRNA.  

Also Read: Difference Between Nucleoside And Nucleotide