KHAEMENES ACADEMY · BIOLOGY 10 · WEEK 24 · DAY 04

Sequence Changes & Protein Outcomes

Compare silent, missense, nonsense and frameshift outcomes without assuming every sequence change has a large phenotype.

Safety, privacy and evidence boundary

Use fictional DNA/RNA/protein sequences and standard codon tables. Do not use personal genomic data or infer disease from sequence examples. Sequence exercises are educational models, not clinical interpretation.

Explicit science instruction

A substitution can be synonymous at the protein level, change one amino acid, or create/remove a stop. Insertions/deletions not in multiples of three can shift the reading frame. Molecular effect depends on location, regulatory context, protein structure, redundancy, and cell biology.

Worked example with reasoning

Original mRNA AUG-GAA-UCU-UGA. Changing GAA to GAG leaves the same amino acid under the standard code: synonymous. Changing GAA to GUA changes one amino acid. Deleting one base can alter downstream grouping entirely.

Guided question

Why is “mutation changes a protein” an overgeneralization?

Independent work

  1. Compare four fictional sequence variants.
  2. Classify molecular outcome.
  3. Translate each.
  4. State why protein change still does not guarantee phenotype change.

Investigation / Data Lab

Codon-table translation comparison

Question: How do different sequence changes alter a translated product under the standard genetic-code model?

  1. Translate a supplied fictional reference mRNA and three variants using the same codon table.
  2. Classify each variant as synonymous, missense, nonsense, or frameshift at the modeled protein level where appropriate.
  3. Count how many downstream amino acids change in each case.
  4. Separate the measured/modelled sequence outcome from any unsupported phenotype claim.
  5. State one limitation of using a short isolated sequence.

Evidence standard: preserve aligned RNA/codon/protein rows and the classification reasoning.

Misconception check

“Silent” usually means synonymous for the encoded amino acid; it does not guarantee zero biological effect on splicing, RNA stability, or regulation.

Formative understanding check

Why can GAA→GAG be synonymous?

Worked response

Both codons specify the same amino acid in the standard genetic code.

Open-book formative practice only; not an official mastery attempt or grade.

Mentor evidence conference

Ask Archaemenes to challenge your information-flow model, sequence reasoning, data interpretation, and limitations.

Open Archaemenes

Teacher guidance

Foundation: use side-by-side codon groups. Core: classify and translate variants. Extended: evaluate regulatory versus coding variants and evidence needed for phenotype claims.

Preserve learning evidence

Keep sequence work, models, corrections, and limitations in the matching Week 24 evidence field.