Transcription and RNA Processing
Introduced| English | Meaning |
|---|---|
| transcription/trænˈskrɪpʃn/ | The production of an RNA molecule using a DNA sequence as its template. |
| RNA polymerase/ˌɑː en ˈeɪ ˌpɒlɪməˈreɪz/ | the enzyme that builds RNA from a DNA template |
| messenger RNA/ˈmesɪndʒə ˌɑː en ˈeɪ/ | An RNA molecule that carries a gene's coding information to a ribosome for protein synthesis. |
Getting the message out
- The DNA master copy stays safely inside the nucleus.
- But proteins are built outside it, in the cytoplasm.
- So the cell makes a working copy of just the gene it needs.
- That copying step is called transcription.
Transcription: DNA to mRNA
- Transcription 转录 copies one gene from DNA into a molecule of RNA.
- The enzyme RNA polymerase RNA聚合酶 reads the DNA template.
- It builds a matching strand of messenger RNA 信使RNA, also called mRNA.
- Only the needed gene is copied, not the whole genome.
Transcription copies a gene from DNA into…
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Transcription makes an mRNA copy of one gene, which can leave the nucleus.
The enzyme that builds the mRNA copy is RNA ____.
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RNA polymerase reads the DNA template and joins RNA nucleotides into mRNA.
Base pairing into RNA
- The mRNA is built by base pairing against the DNA template.
- A DNA T gives an mRNA A; a G gives a C; a C gives a G.
- But a DNA A gives an mRNA U, because RNA uses uracil.
- The result is an RNA copy of the gene's message.
Transcription: DNA to mRNA
Step through transcription - the DNA template is copied into mRNA by base pairing (A to U, T to A, G to C, C to G).
When transcribing DNA into mRNA, a DNA "A" is copied as an mRNA…
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RNA uses uracil, so a DNA A pairs with an mRNA U (DNA T → mRNA A, G → C, C → G).
RNA processing
- In eukaryotes, the new mRNA is edited before it leaves the nucleus.
- Useless sections are cut out and the useful ones are joined.
- The ends are capped to protect the message.
- Now the finished mRNA can travel out to a ribosome.
In eukaryotes, the mRNA is edited (processed) before it leaves the nucleus.
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RNA processing trims and caps the mRNA so it is ready to be read by a ribosome.
Select all true statements about transcription.
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Transcription copies one gene, not the whole genome. The other three are correct.
Transcription copies one gene at a time, not all the DNA. And the DNA itself stays in the nucleus — only the mRNA copy travels out. Think of photocopying a single page from a reference book you are not allowed to remove.
Making insulin's message:
- To make insulin, a cell transcribes just the insulin gene.
- RNA polymerase copies it into mRNA; the rest of the DNA is untouched.
- The processed mRNA leaves the nucleus, carrying the recipe to the protein factory.
Transcription copies one gene from DNA into messenger RNA (mRNA), built by RNA polymerase through base pairing (with U in place of T). In eukaryotes the mRNA is then processed — trimmed and capped — before leaving the nucleus to carry the message to a ribosome.
Write from an mRNA codon of AUG
- The DNA template strand reads 3 prime TAC 5 prime.
- RNA uses uracil where DNA would use thymine.
What mRNA codon is transcribed, 5 prime to 3 prime?
Transcription builds RNA complementary to the template.
What mRNA comes from the template 3 prime TAC 5 prime?
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The message is complementary and uses uracil.