A synthetic mRNA transcript used in a gene-therapy trial contains a coding region of exactly 489 nucleotides. During the process of translation, ribosome complexes read the nucleotides in non-overlapping triplets known as codons. Each codon corresponds to a single amino acid, with the exception of the terminal stop codon, which terminates translation without contributing an amino acid to the polypeptide chain.
Assuming this transcript begins with a start codon and terminates with a single stop codon:
Determine the total number of codons in this mRNA transcript.
Calculate the final number of amino acids in the synthesised polypeptide chain.
76 exam-style questions on AQA GCSE Biology 6.1 Reproduction, covering 6.1.1 Sexual and asexual reproduction, 6.1.2 Meiosis, 6.1.3 Advantages and disadvantages of sexual and asexual reproduction, 6.1.4 DNA and the genome, 6.1.5 DNA structure, 6.1.6 Genetic inheritance, 6.1.7 Inherited disorders, and 6.1.8 Sex determination. Each one has a worked solution and a mark scheme showing where the marks go.