Question:
Read the following passage and answer the questions that follow :
The process of copying genetic information from template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
(b) (i) Why is hnRNA required to undergo splicing ?
Read the following passage and answer the questions that follow :
The process of copying genetic information from template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.
(b) (i) Why is hnRNA required to undergo splicing ?
Show Hint
hnRNA has introns that must be cut out and exons that must be joined.
Updated On: Oct 22, 2026
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Solution and Explanation
Step 1: Recall what hnRNA is:
hnRNA (heterogeneous nuclear RNA) is the primary transcript made by RNA polymerase II in eukaryotes.
It contains both exons (coding sequences) and introns (non-coding sequences).
Step 2: Why splicing is needed:
Introns carry no code for the protein. If they stayed, the mRNA would give a wrong or useless protein.
In splicing the introns are removed and the exons are joined in a defined order.
Only the spliced RNA, after capping and tailing, becomes a functional mRNA that ribosomes can translate.
Final Answer:
hnRNA must be spliced to remove the non-coding introns and join the exons, so that a functional mRNA is formed.
hnRNA (heterogeneous nuclear RNA) is the primary transcript made by RNA polymerase II in eukaryotes.
It contains both exons (coding sequences) and introns (non-coding sequences).
Step 2: Why splicing is needed:
Introns carry no code for the protein. If they stayed, the mRNA would give a wrong or useless protein.
In splicing the introns are removed and the exons are joined in a defined order.
Only the spliced RNA, after capping and tailing, becomes a functional mRNA that ribosomes can translate.
Final Answer:
hnRNA must be spliced to remove the non-coding introns and join the exons, so that a functional mRNA is formed.
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