Molecular Basis of Inheritance
Translation
Translation is the ribosome reading the RNA message three letters at a time and joining amino acids in that order to build a protein.
The messenger RNA is read in blocks of three bases called codons. Each codon calls for one amino acid. Transfer RNA (tRNA) molecules bring the matching amino acids, and the ribosome links them into a chain.
Reading starts at a start codon (AUG) and ends at a stop codon. The finished chain of amino acids folds into a working protein. This is the last step of the flow from gene to protein.
Where students slip up
The code is read in non-overlapping triplets, and the reading frame matters. Add or delete one base and every codon after it shifts, so the whole protein changes. Students often read codons as single letters or forget that the starting point sets the frame.
Hold onto this
Three bases, one amino acid. Start at AUG, stop at a stop codon.
Why it helps in the exam: codon-to-amino-acid reading, start and stop codons, and the role of tRNA recur every year.
Where this connects
A protein's job is set by its amino acid order, which is set by the codon order, which came straight from the gene. Change one DNA base and you can change one amino acid, which is how a single mutation causes sickle cell anaemia.
Back to where the message came from →Quick check
In translation, how many bases of mRNA code for one amino acid?
- AOne
- BTwo
- CThree
- DFour