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The table shows the positions of bases in the mRNA codons for specific amino acids - Scottish Highers Human Biology - Question 5 - 2018
Question 5
The table shows the positions of bases in the mRNA codons for specific amino acids. First position Second position Third position U phenylalanine tyrosine... show full transcript
Worked Solution & Example Answer:The table shows the positions of bases in the mRNA codons for specific amino acids - Scottish Highers Human Biology - Question 5 - 2018
Step 1
Which of the following mutations in a section of mRNA would result in the production of a shortened protein?
Answer
To determine which mutation results in a shortened protein, we should analyze the mutated mRNA codons given in the options.
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Original Codons: AUG GGC CAU
- AUG: Methionine (start)
- GGC: Glycine
- CAU: Histidine
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Mutated Options:
- A: AUG GCU CAU - GCU codes for Alanine.
- B: CAG UAG UGG - UAG is a stop codon (this would shorten the protein).
- C: CAG UAG UGG - Same as Option B.
- D: GUC AAC UGG - GUC codes for Valine and does not introduce a stop codon.
- E: GUC AAG UGG - AAG codes for Lysine, no stop codon.
From this analysis, the correct choice is B, as it includes a stop codon that would lead to the premature termination of protein synthesis.