---
title: "Transcription and RNA Splicing in Eukaryotes"
description: "RNA polymerase copies one strand into pre-mRNA, and introns are cut out before the message leaves the nucleus. Splicing is why one gene can give more than one protein."
canonical: https://lightmysky.com/learn/science/transcription-and-rna-splicing-in-eukaryotes-mt_j2vc70vH5t
source: https://lightmysky.com/learn/science/transcription-and-rna-splicing-in-eukaryotes-mt_j2vc70vH5t.md
retrieved: 2026-09-12
---

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# Transcription and RNA Splicing in Eukaryotes

RNA polymerase copies one strand into pre-mRNA, and introns are cut out before the message leaves the nucleus. Splicing is why one gene can give more than one protein.

Subject: Science · Area: Genetics & Evolution · Ages 16 to 17
Page: https://lightmysky.com/learn/science/transcription-and-rna-splicing-in-eukaryotes-mt_j2vc70vH5t

## Ready when they can

- Says which DNA strand acts as the template and what the immediate product is.
- Distinguishes introns from exons by what happens to each before translation.
- Explains how alternative splicing lets one gene produce different proteins.

## Lesson: From gene to edited message

RNA polymerase copies one strand of a gene into RNA. It reads the template strand and builds pre-mRNA, pairing U with A, A with U, G with C and C with G. The coding strand is left alone, and it matches the new RNA. This rough first copy is called pre-mRNA.

Eukaryotic genes mix useful exons with silent introns. A machine called the spliceosome cuts out every intron and joins the exons into one message. A cap and a tail are added to protect the ends and mark the message ready. Only the finished mRNA leaves the nucleus for the ribosomes.

**Example.** One gene can make several different proteins. Nerve cells and muscle cells share genes, yet they keep different sets of exons and build different proteins. This remix is called alternative splicing: one gene, many messages.

**Tip.** Keep two pairs apart: the template is read while the coding strand is matched, and introns are cut while exons are kept. Introns never reach the ribosome, so they are never translated.

**Recap.** Copy the template into pre-mRNA, cut out the introns, join the exons, and ship the mature message out.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [From Gene to Protein](https://lightmysky.com/learn/science/from-gene-to-protein-mt_PdNyzTl8Ye)
- [Semi-conservative DNA Replication](https://lightmysky.com/learn/science/semi-conservative-dna-replication-mt_wIcBfUw295)

## Opens up

- [Transcription Initiation: Promoters, General Factors and Polymerase Recruitment](https://lightmysky.com/learn/science/transcription-initiation-promoters-general-factors-and-polymerase-recruitment-mt_0Ky-pYgh0Y)
- [Translation at the Ribosome](https://lightmysky.com/learn/science/translation-at-the-ribosome-mt_1EdZzeqts1)
- [Chromatin: Nucleosomes and Higher-Order Packing](https://lightmysky.com/learn/science/chromatin-nucleosomes-and-higher-order-packing-mt_5q3Hsdqm9x)
- [Transcription Factors and Epigenetic Control](https://lightmysky.com/learn/science/transcription-factors-and-epigenetic-control-mt_nF4JJ_EDa4)
- [Alternative Splicing and One Gene, Many Proteins](https://lightmysky.com/learn/science/alternative-splicing-and-one-gene-many-proteins-mt_xei9v3IIsE)