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MCAT Biology & Codon Practice
Practice high-yield MCAT Bio/Biochem topics with one-question-at-a-time feedback.
Answer one question at a time. After you choose an option, the page shows the correct answer and explanation, then you continue with Next.
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Gene expression
Easy
Recall
Which codon is the canonical start codon in the standard genetic code?
What to focus on
Start with gene expression, biomolecules, cell biology, metabolism, and organ systems. These are the Bio/Biochem areas most useful for this site.
Gene expression: replication, transcription, RNA processing, translation, and mutations.
Biomolecules: amino acids, proteins, enzymes, lipids, carbohydrates, and nucleotides.
Cell biology: organelles, membranes, viruses, mitosis, and meiosis.
Organ systems questions often test mechanism and process order, not just terms.
Keep practicing
Stay inside the site and move between the quiz, lookup tools, and memorization aids.
Common questions
Do I need to memorize all 64 codons for MCAT?
Usually not. You should know the start and stop codons, the general idea of degeneracy, and how translation uses codons and anticodons.
What should I practice next?
Use the codon table, then move to the DNA to Protein Converter or amino acid code reference to drill the same concepts from a different angle.
Why are some codon changes silent?
Because the genetic code is degenerate. A different codon can still encode the same amino acid, especially when the change happens in the third base.