Question

Define exon and intron.

Short answer

Exons are coding regions; introns are non-coding regions.

Step-by-step solution

- Define Exon

An exon is a segment of a DNA or RNA molecule that contains coding information for a protein. These segments are expressed, meaning they are transcribed into mature messenger RNA (mRNA) and eventually translated into the amino acid sequence of proteins.

- Define Intron

An intron, on the other hand, is a segment of a DNA or RNA molecule that does not contain coding information for a protein. Introns are non-coding regions that are transcribed into primary RNA transcripts but are removed during RNA splicing before the mRNA matures.

Key concepts

Exon

An exon is an essential segment of a DNA or RNA molecule that contains the coding information necessary for protein synthesis. Unlike non-coding regions, exons are destined to be expressed. Here is what exons do:

• They are transcribed into mature messenger RNA (mRNA).
• This mRNA is then translated into the amino acid sequences that form proteins.

Exons work alongside other exons in sequential order to build a complete blueprint for a protein. They are crucial for understanding how genes are expressed and how proteins are created in living organisms.

Intron

Introns are segments of DNA or RNA that do not encode proteins. Although they are transcribed into RNA, they do not contribute to amino acid sequences in proteins. Here are some key points about introns:

• They are found within the genes that contain coding sequences.
• During the transcription process, introns are copied into RNA.
• However, they are removed during a process called RNA splicing.

Introns serve various roles such as regulating gene expression and enabling alternative splicing, which allows a single gene to code for multiple proteins.

RNA Splicing

RNA splicing is a critical step in the process of converting the genetic information stored in DNA into functional proteins. This process removes introns and joins exons together. Key steps during RNA splicing include:

• Recognition of intron-exon boundaries by the spliceosome.
• Removal of introns from the primary RNA transcript.
• Ligation of exons to produce a continuous coding sequence.

RNA splicing is essential for generating mature mRNA, which will be translated into proteins. Additionally, RNA splicing allows for alternative splicing, leading to the diversity of proteins produced from a single gene.

mRNA

Messenger RNA (mRNA) is a type of RNA that carries genetic information from DNA in the cell nucleus to ribosomes in the cytoplasm. Here’s why mRNA is vital:

• It serves as a template for protein synthesis.
• mRNA is synthesized during transcription, where the DNA sequence of a gene is copied into mRNA.
• After transcription, mRNA undergoes RNA splicing to become mature mRNA, ready for translation.

Mature mRNA is crucial for interpreting genetic codes and synthesizing proteins correctly, which are necessary for various cellular functions and overall organism health.