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Transcription and translation both run 5' to 3', which keeps the genetic message in the right order
- Nucleic acids are read and built in one fixed direction, described as 5' to 3'.
- This fixed direction is what lets genetic information be copied and translated accurately.
The 5' and 3' labels come from the carbon atoms of the sugar
- Nucleic acids like DNA and RNA have a direction because each nucleotide is asymmetric.
- A phosphate group is attached to the 5' carbon of the sugar.
- A hydroxyl group (-OH) is attached to the 3' carbon.
Analogy
- Picture a train track where one end is the start (5') and the other is the destination (3').
- The train, which stands for the enzyme, can only travel one way.
RNA polymerase builds RNA by adding nucleotides to the 3' end
- During transcription, RNA polymerase reads the DNA template strand and builds a complementary RNA strand.
