Biology / Unit 6: DNA and Protein Synthesis
6.3 RNA and Transcription
Notes
RNA carries the instructions from DNA to the ribosomes. The central dogma is DNA → RNA → protein.
- RNA differs from DNA: it is single-stranded, has the sugar ribose, and uses uracil (U) instead of thymine.
- mRNA (messenger) carries the code; tRNA (transfer) brings amino acids; rRNA (ribosomal) forms ribosomes.
- Transcription copies a gene from DNA into mRNA. It happens in the nucleus in eukaryotes.
- RNA polymerase builds the mRNA. In RNA, A pairs with U.
- In eukaryotes, introns are cut out of mRNA and exons are kept.
Practice
A DNA template strand reads TACGGA. What mRNA is transcribed?
T pairs with A, A pairs with U, C pairs with G, G pairs with C.
Which base is found in RNA but not in DNA?
RNA uses uracil in place of thymine.
Where does transcription happen in a eukaryotic cell?
DNA stays in the nucleus, so mRNA is made there.
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