Physics Wallah is an Indian edtech platform that provides accessible & comprehensive learning experiences to students from Class 6th to postgraduate level. We also provide extensive NCERT solutions, sample paper, NEET, JEE Mains, BITSAT previous year papers & more such resources to students. Physics Wallah also caters to over 3.5 million registered students and over 78 lakh+ Youtube subscribers with 4.8 rating on its app.
We Stand Out because
We provide students with intensive courses with India’s qualified & experienced faculties & mentors. PW strives to make the learning experience comprehensive and accessible for students of all sections of society. We believe in empowering every single student who couldn't dream of a good career in engineering and medical field earlier.
Our Key Focus Areas
Physics Wallah's main focus is to make the learning experience as economical as possible for all students. With our affordable courses like Lakshya, Udaan and Arjuna and many others, we have been able to provide a platform for lakhs of aspirants. From providing Chemistry, Maths, Physics formula to giving e-books of eminent authors like RD Sharma, RS Aggarwal and Lakhmir Singh, PW focuses on every single student's need for preparation.
What Makes Us Different
Physics Wallah strives to develop a comprehensive pedagogical structure for students, where they get a state-of-the-art learning experience with study material and resources. Apart from catering students preparing for JEE Mains and NEET, PW also provides study material for each state board like Uttar Pradesh, Bihar, and others
Q. What are the three post-transcriptional modifications?
Ans. The three primary post-transcriptional modifications are capping, tailing, and splicing. These steps convert hnRNA into functional mRNA by adding a 5' cap, a 3' poly-A tail, and removing non-coding introns.
Q. What is a post-transcriptional modification in transcription?
Ans. Post-transcriptional modification refers to the changes that occur after transcription, including the processing of hnRNA into mature mRNA. It involves capping, tailing, and splicing to ensure RNA stability and functionality.
Q. Why is post-transcriptional modification absent in prokaryotes?
Ans. Prokaryotes lack a nucleus, and their transcription and translation occur simultaneously in the cytoplasm. As a result, there is no need for RNA processing, and hnRNA is not formed.
Q. Is RNA splicing a post-transcriptional modification?
Ans. Yes, RNA splicing is a key post-transcriptional modification. It involves removing introns and joining exons to produce mature mRNA suitable for translation.
Post Transcriptional Modification, Process and Significance
Post Transcriptional Modification, Learn about post-transcriptional modification, including capping, tailing, and splicing, and understand their significance in biology.
Krati Saraswat5 Jun, 2025
Share
Post transcriptional modification is a crucial process in eukaryotic cells that plays a key role in converting the newly synthesized RNA , called heterogeneous nuclear RNA (hnRNA), into functional messenger RNA (mRNA). This process is vital for ensuring that mRNA is properly processed, stable, and ready for translation into proteins. Post-transcriptional modifications include capping, tailing, and splicing, all of which are necessary for the proper expression of genes. Understanding these processes is important for biology and the NEET exam , as they form the foundation of molecular biology and gene expression mechanisms.
Post Transcriptional Modification Overview
Post transcriptional modification is a crucial step in the processing of heterogeneous nuclear RNA (hnRNA) into mature messenger RNA (mRNA) that is ready for translation. This process is unique to eukaryotic cells and is absent in prokaryotes. In eukaryotes, the primary RNA transcript (hnRNA) produced during transcription contains both coding regions (exons) and non-coding regions (introns). Because of the presence of introns, the hnRNA is non-functional and must undergo specific modifications to become a functional mRNA. These modifications ensure the stability of mRNA, aid in its transport from the nucleus to the cytoplasm, and facilitate accurate protein synthesis.
Steps involved in post-transcriptional modification of hnRNA
The major steps involved in post-transcriptional modification include capping, tailing, and splicing.
Capping
Capping occurs at the 5' end of the hnRNA. A unique nucleotide, methyl guanosine triphosphate (mGppp), is added to the 5' end. This cap protects the RNA from degradation by exonucleases and facilitates ribosome binding during translation. Capping is the first modification to occur during RNA processing.
Tailing
At the 3' end of hnRNA, a series of adenine residues (200–300) are added, forming a poly-A tail. This process, called polyadenylation, is template-independent. The poly-A tail enhances the stability of mRNA and aids in its transport from the nucleus to the cytoplasm .
Splicing
Splicing is the most critical step in post-transcriptional modification. Introns, which are non-coding sequences, are removed from the hnRNA. The remaining exons, which are coding sequences, are joined together to form mature mRNA. This step ensures that the RNA transcript can be translated into a functional protein.
Process of Splicing
Splicing begins when the snRNPs attach to specific sequences at the 5’ and 3’ ends of introns in the hnRNA. These sequences act as signals for splicing.
Spliceosome Formation: The snRNPs bind to the intron regions and form a spliceosome, which is a large complex that facilitates the cutting and joining process.
Intron Removal: The spliceosome excises the introns by cutting them out at the designated sites.
Exon Joining: After intron removal, the remaining exons are joined together by RNA ligase to form the mature mRNA.
This precise process is vital to ensure that the final mRNA contains only coding regions. Errors in splicing can lead to the production of defective proteins, which may result in diseases or cellular dysfunctions.
Significance of Post-Transcriptional Modification
Post-transcriptional modifications are essential for producing functional mRNA from hnRNA. These modifications include capping, tailing, and splicing, which ensure mRNA stability, proper transport to the cytoplasm, and accurate protein synthesis.
mRNA Stability: The 5' cap and 3' poly-A tail protect mRNA from degradation, allowing it to persist in the cytoplasm for translation.
mRNA Export: The modifications signal the transport of mRNA from the nucleus to the cytoplasm for protein synthesis.
Proper Protein Synthesis: Splicing removes introns and joins exons to form a functional mRNA sequence.
Gene Expression Regulation: These modifications regulate mRNA stability and translation, influencing protein production.
MCQs of Post Transcriptional Modification
Q1. Capping is a process in which;
adenylate is added at 5' end.
methyl guanosine triphosphate is added at 5' end.
adenylate is added at the 3' end.
methyl guanosine triphosphate is added at 3' end.
Q2. Splicing is meant to eliminate;
cistrons
mutons
exons
introns
Q3. Methyl guanosine triphosphate is added at 5' end of hnRNA in a process of;
(1) Tailing (2) Splicing (3) Capping (4) None of these
Answers of MCQs of Post Transcriptional Modification
Ans1. Methyl guanosine triphosphate is added at 5' end., Ans2. Introns, Ans3. Capping Unlock your path to success with PW's comprehensive NEET preparation resources , which include useful guidance, personalized study plans, mock tests, and PW Online NEET Coaching , which are designed to help you achieve your dream medical college.
