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
Ribosomes read mRNA in nonoverlapping three-base codons. Transfer RNAs carry amino acids and use anticodons to pair with codons. Translation usually begins at a start codon in the selected reading frame and ends at a stop codon.
The standard code is degenerate: multiple codons can specify the same amino acid. It is nearly universal but has known biological exceptions.
Worked example with reasoning
mRNA 5′-AUG GCU UUU UGA-3′ translates Met-Ala-Phe-Stop using the standard code. The codon is on mRNA; the tRNA anticodon is complementary and antiparallel.
Guided question
Why can shifting the reading frame change every downstream codon?
Independent work
- Translate three fictional mRNAs.
- Identify start and stop.
- Write one tRNA anticodon correctly oriented.
- Explain code degeneracy.
Misconception check
A codon is not an amino acid itself; it is an RNA sequence interpreted by the translation machinery.
Formative understanding check
What amino acid does AUG specify in the standard table?
Worked response
Methionine and commonly the start signal.
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 ArchaemenesTeacher guidance
Foundation: use a codon wheel/table. Core: translate and track frame. Extended: compare codon degeneracy with wobble conceptually and note code exceptions.
Preserve learning evidence
Keep sequence work, models, corrections, and limitations in the matching Week 24 evidence field.