Anatomy and Physiology 12 · Biology · Lesson 4.2
Transcription
- Level
- Grade 12
- Reading time
- 13 min reading
- Review
- Last reviewed 2026-09-03
- Standard
- Accuracy standard
- Errata
Abstract
DNA to mRNA.
What is transcription in protein synthesis?
Short answer
Transcription is the first stage of protein synthesis, in which the DNA sequence of a gene is copied into messenger RNA (mRNA). The enzyme RNA polymerase reads one DNA strand and builds a complementary mRNA strand, using uracil in place of thymine. The mRNA then carries the genetic message from the nucleus to the ribosome for translation.
Concept preview
What you will be able to do
- 01State the central dogma and describe the flow of information from DNA to RNA to protein.
- 02Describe how RNA differs from DNA and why cells make RNA copies of genes.
- 03Explain the roles of the promoter, RNA polymerase and the template strand in transcription.
- 04Describe how eukaryotic pre-mRNA is processed with a 5′ cap, poly-A tail and splicing.
- 05Explain why mature mRNA leaves the nucleus to be translated in the cytoplasm.
The information stored in DNA is far too precious to risk using directly, so a cell almost never does. Instead it follows a strict, two-step flow of information that biologists call the central dogma: DNA to RNA to protein. First, the instructions written in a gene are copied into a portable working copy made of RNA, in a step called transcription. Then that RNA copy is read to build a protein, in a step called translation. It helps to picture the DNA as a library reference book that must never leave the building, and the RNA as a photocopy of a single page that can be carried out to the workbench where the actual work is done.
School Plan
Transcription
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Related topics
Frequently asked questions
- What enzyme carries out transcription?
- RNA polymerase, which reads the DNA template strand and assembles a complementary mRNA molecule.
- How does transcription differ from replication?
- Replication copies all of the DNA into DNA; transcription copies one gene into RNA, using uracil instead of thymine.