Life sciences, genetics, gene expression / principles and exploration
Transcription, translation, and mutations — principles and investigation
Base changes in DNA can have different effects on transcribed RNA and translated proteins. Apply substitutions, insertions, and deletions in short base sequences and compare codon and amino acid changes. This is an activity that distinguishes between replacement of a single base and frameshift, in which the reading frame itself changes.
How does it work?
ATG GCT TGG TAA is Met-Ala-Trp-termination. Substitutions can create silent mutations, missense, or nonsense, and single-base insertions/deletions can create frameshift.
DNA template → mRNA (5′→3′) → codon → amino acid
Try this investigation
- The code strand is marked 5′→3′, and the template strand is marked 3′→5′. Select the mutation method and base and click the base button. The insertion occurs immediately after the base you clicked.
- Perform GCT→GCC mutation on the reference sequence and record the amino acid and termination positions.
- Compare TGG→TGA and the insertion of 1 base after the first codon. You can return to the original sequence button.
Interpreting your results
What mutation occurs if one base is inserted after the first codon?
Codons are read three bases at a time from a designated starting point. Insertions and deletions that are not multiples of 3 change the reading frame. Translation stops before the stop codon.
Assumptions and limitations
It is a reading frame that uses 64 standard genetic codes and fixes the first base of the code strand. Start codon search, intron removal, regulation, and protein folding are omitted. ATG start loss is also translated into a fixed frame. Mutation determination is compared to a reference sequence, and changes after termination are seen as silent mutations in this short protein. Translation stops at the first termination and the remaining incomplete codons are not translated. It does not predict actual function or disease.