Translation: building a protein from RNA — Biology, 14–17
Translation is the stage where a ribosome reads an RNA message and joins amino acids in the right order. The order matters because it guides the protein’s shape and job.
A ribosome reads three-letter words
A ribosome moves along messenger RNA and reads its bases in groups of three. Each group, called a codon, points to an amino acid or gives a start or stop signal. Transfer RNA molecules bring matching amino acids, allowing the ribosome to build a chain that can fold into a working protein.
Why the message needs decoding
RNA uses a sequence of bases, but proteins use a sequence of amino acids: they are different chemical languages. Translation solves the problem of turning one sequence into the other. The genetic code makes this possible, with several codons often pointing to the same amino acid and three codons marking the end.
Reading AUG–GGC–UAA
Start with the mRNA sequence AUG–GGC–UAA. First, AUG tells the ribosome to start and adds methionine. Next, GGC adds glycine. Finally, UAA is a stop codon, so no amino acid is added for it. The short product is therefore methionine–glycine, not three amino acids.
“One codon means one gene”
It is easy to mix up scales: a codon is three RNA bases, while a gene is a much longer stretch of DNA that can help specify a whole protein or part of one. A codon usually names one amino acid, but a gene contains many codons plus signals that control when its message is used.
From genes to medicines
Many medicines are proteins made by cells or by engineered microbes. Scientists can place a human gene into bacteria, then let bacterial ribosomes translate its RNA and produce a useful molecule such as insulin. The protein must still fold correctly and be purified before it can be used safely.
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