Translation
Translation is where a sequence of bases finally becomes a sequence of amino acids, and Topic 6.4 is where you learn exactly what reads what. The ribosome reads mRNA — not DNA — moving along the messenger strand three bases at a time. Each three-base unit on the mRNA is a codon, and the ribosome never touches the original DNA template during this step: the DNA stayed in the nucleus, and its message was carried out as mRNA in transcription. Keeping straight which molecule the ribosome is actually reading is the foundation everything else here rests on.
The match happens through transfer RNA (tRNA). Every tRNA carries a specific amino acid on one end and a three-base anticodon on the other. When an mRNA codon is exposed in the ribosome, the tRNA whose anticodon is complementary to that codon binds, and its amino acid is added to the growing chain. Codon and anticodon are not the same thing read twice — the codon lives on the mRNA, the anticodon lives on the tRNA, and they pair as complements. Confusing the two, or forgetting that tRNA is the physical bridge between the message and the protein, is where most of the trouble starts.
Interactive · Translation
Step the ribosome along an mRNA strand one codon at a time, watch each tRNA match its anticodon to the exposed codon, and see the amino acid it carries snap onto the growing chain. Notice that it is the mRNA — not DNA — being read, and that codon and anticodon are complementary partners, not copies.
Translation · Open the full sandbox →The mistakes here cluster around two failure modes. One is mistaking what the ribosome reads — imagining it reading DNA directly, when the ribosome reads mRNA and the DNA never leaves to be translated. The other is conflating codon and anticodon — forgetting that the codon sits on the mRNA while the complementary anticodon sits on the tRNA that delivers the amino acid. Every scenario in this topic asks you to keep the ribosome reading the right molecule and to keep codon, anticodon, and tRNA in their proper places.
The work
3 ways in · any order
Lesson
Translation
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The ribosome reads mRNA — not DNA — one codon at a time, and each mRNA codon pairs with the complementary anticodon of a tRNA that delivers the matching amino acid. The lesson walks the ways students misread that: imagining the ribosome reading DNA directly, and blurring codon into anticodon. It closes with a ten-scenario applet that asks you to keep the ribosome reading the right molecule and codon, anticodon, and tRNA in their proper places.
Diagnostic
10-item topic check
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Ten items on translation — that the ribosome reads mRNA, not DNA, as it builds the protein (U6-BIO8); that each mRNA codon is matched by a complementary tRNA anticodon, so codon and anticodon are distinct and shouldn't be conflated (U6-BIO9); and that the flow runs DNA → RNA → protein, with the mRNA never skipped and tRNA delivering each amino acid to the growing chain (U6-BIO1). Take it cold to surface which of these are still tangled, or after the lesson to confirm they hold.
Targeted Practice
Drill a single misconception
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Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.