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Gene Mutation

High schoolBiologyShort coding-sequence substitution, insertion or deletion with explicit alignment, standard-code decoding and categorical sequence comparisons

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About this experiment

Edit a chosen DNA position and compare the exact sequence before and after the change. Alignment gaps expose insertions and deletions, while codon decoding shows which amino-acid strings change. Preset examples separate silent changes, missense substitutions, early stops and frame shifts without claiming to predict protein function.

Learning goals

  • Distinguish a base substitution from an insertion or deletion.
  • Connect insertion length modulo three with reading-frame preservation.
  • Compare sequence-level categories while recognizing limits of codon lookup.

How to use it

  1. 1Apply the silent example and compare altered DNA with unchanged amino-acid lookup.
  2. 2Apply the missense and early-stop examples and inspect changed residues and stop position.
  3. 3Insert one base and compare it with an insertion of three bases.
  4. 4Choose a different reference position, apply an edit and record both sequences and its category.

The model

Frame-preserving sequence-length change
Frameshifting sequence-length change

Assumptions

  • The reference is a short intron-free coding sequence. All decoding uses frame one and the standard genetic code, stopping at its first in-frame stop.
  • Inserted bases repeat the selected symbol. Deletion removes up to the selected number of available bases. Gaps appear only in alignment, not in the sequence used for decoding.
  • A changed original ATG start is flagged separately. The decoder does not model initiation, splicing, RNA stability, protein folding, activity or organism-level effects. In-frame indels may also alter local codons or stop signals.

Try this in class

  1. Q1Why can a DNA change leave the decoded amino-acid string unchanged?
  2. Q2Why does adding three bases preserve the downstream frame even when nearby codons change?

Frequently asked questions

Is a synonymous edit guaranteed to have no biological consequence?

No. Unchanged codon-decoded amino acids do not account for regulation, processing or other sequence-dependent effects.

Does an earlier stop always mean this model predicts the real protein?

No. It describes an in-frame sequence change under the stated decoder, not actual initiation or expression.