Asked by: Yiwen Mercker
science genetics

What is the purpose of an intron?

Last Updated: 28th April, 2020

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While introns do not encode protein products, they are integral to gene expression regulation. Some introns themselves encode functional RNAs through further processing after splicing to generate noncoding RNA molecules. Alternative splicing is widely used to generate multiple proteins from a single gene.

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Similarly, you may ask, what is the purpose of introns and exons?

intron / introns. In some genes, not all of the DNA sequence is used to make protein. Introns are noncoding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein. The sections of DNA (or RNA) that code for proteins are called exons.

Similarly, why are introns removed? Not only do the introns not carry information to build a protein, they actually have to be removed in order for the mRNA to encode a protein with the right sequence. If the spliceosome fails to remove an intron, an mRNA with extra "junk" in it will be made, and a wrong protein will get produced during translation.

Consequently, why do introns exist?

Eukaryotes might need this diversity in proteins because they have many types of cells all with the same set of genes. Therefore, introns are a way to generate different proteins or different amounts of proteins that are unique to a cell type. Introns might also allow for faster evolution.

What are two functions of introns?

Introns serve at least two functions. One, acting as spacers between coding gene regions, they facilitate alternative splicing of genes. The benefit here is protein diversity; it's how our cells can express 100K proteins from only 20K genes.

Related Question Answers

Abelia Bilsk

Professional

What is the benefit of introns?

Introns are crucial because the protein repertoire or variety is greatly enhanced by alternative splicing in which introns take partly important roles. Alternative splicing is a controlled molecular mechanism producing multiple variant proteins from a single gene in a eukaryotic cell.

Xiaoguang Fornaguera

Professional

Are introns junk DNA?

Although introns have sometimes been loosely called "junk DNA," the fact that they are so common and have been preserved during evolution leads many researchers to believe that they serve some function.

Himo Salaet

Professional

Where does splicing occur?

For nuclear-encoded genes, splicing takes place within the nucleus either during or immediately after transcription. For those eukaryotic genes that contain introns, splicing is usually required in order to create an mRNA molecule that can be translated into protein.

Khdija Membiela

Explainer

Are introns transcribed?

In most eukaryotic genes, coding regions (exons) are interrupted by noncoding regions (introns). During transcription, the entire gene is copied into a pre-mRNA, which includes exons and introns. During the process of RNA splicing, introns are removed and exons joined to form a contiguous coding sequence.

Malgorzata Crippa

Explainer

What is alternative splicing and why is it important?

Alternative splicing of RNA is a crucial process for changing the genomic instructions into functional proteins. It plays a critical role in the regulation of gene expression and protein diversity in a variety of eukaryotes. In humans, approximately 95% of multi-exon genes undergo alternative splicing.

Rhimo Jyotiradha

Explainer

Are introns coding or noncoding?

Introns are non-coding sections of a gene, transcribed into the precursor mRNA sequence, but ultimately removed by RNA splicing during the processing to mature messenger RNA. Many introns appear to be mobile genetic elements.

Geeta Llido

Pundit

What do exons do?

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. The term exon refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts.

Hristiyan Turyanov

Pundit

Are introns useless?

Introns are NOT considered useless. Its just that they do not code for protiens. But they have evolutionary and genetic significance. Point mutations within introns can lead to defective splicing.

Ilias Gudelius

Pundit

Who discovered junk DNA?

The term “junk DNA” was first used in the 1960s, but was formalized by Susumu Ohno in 1972. Ohno noticed that the amount of mutation occurring as a result of deleterious mutations set a limit for the amount of functional loci that could be expected when a normal mutation rate was considered.

Naveeda Graham

Pundit

What is mRNA made of?

Messenger RNA (mRNA) Messenger RNA (mRNA) is a single-stranded RNA molecule that is complementary to one of the DNA strands of a gene. The mRNA is an RNA version of the gene that leaves the cell nucleus and moves to the cytoplasm where proteins are made.

Huber Jover

Teacher

Are introns removed?

Introns are removed by RNA processing in which the intron is looped out and cut away from the exons by snRNPs, and the exons are spliced together to produce the translatable mRNA.

Bouselham Nunn

Teacher

Are promoters transcribed?

A promoter is a sequence of DNA needed to turn a gene on or off. The process of transcription is initiated at the promoter. Usually found near the beginning of a gene, the promoter has a binding site for the enzyme used to make a messenger RNA (mRNA) molecule.

Elfi Vondenhagen

Teacher

What do genes code for?

The genome of an organism is inscribed in DNA, or in some viruses RNA. The portion of the genome that codes for a protein or an RNA is referred to as a gene. Those genes that code for proteins are composed of tri-nucleotide units called codons, each coding for a single amino acid.

Ahlalia Kabigertua

Teacher

Are introns in prokaryotes?

Prokaryotes can't have introns, because they have transcription coupled to translation. They don't have time/space for that, since intron splicing will stop the coupling. Eukaryotes evolved the nucleus, where splicing can be done.

Fran Troyanowsk

Reviewer

Do viruses have introns?

Viruses have introns and exons; they carry genomes in either DNA or RNA form and once in the host cell, they replicate or carry out transcription (which includes excision of introns) and then they subsequently use the host ribosomes to translate the mRNAs into proteins for viral assembly.

Procopio Novikova

Reviewer

What if introns were not removed?

If introns were not edited out of the RNA strand, the RNA strand would probably have many problems. Errors would most likely occur in the instruction code for amino acids and proteins and the cell therefore would not get the amount of proteins needed.

Xiuyun Balfego

Reviewer

What happens during splicing?

RNA splicing is the removal of introns and joining of exons in eukaryotic mRNA. It also occurs in tRNA and rRNA. They locate the ends of the introns, cut them away from the exons, and join the ends of adjacent exons together. Once the entire gene is devoid of its introns, the process of RNA splicing is complete.

Louhou Mouga

Reviewer

Do introns have codons?

The main thing to remember is that exon and introns are features of DNA, whereas codons are features of RNA. By definition, exons and introns are sequences in a protein-coding gene region of a double-stranded DNA molecule (dsDNA) that are expressed as proteins, or intervening sequences not so expressed.

Roa Cortico

Supporter

Do archaea have introns?

Abstract. Group I catalytic introns have been found in bacterial, viral, organellar, and some eukaryotic genomes, but not in archaea. All known archaeal introns are bulge-helix-bulge (BHB) introns, with the exception of a few group II introns.