What would happen if in a gene encoding a polypeptide of 50 amino acid...
UAA is the stop codon. Therefore at 25th amino acid the synthesis of polypeptide stops. So, a polypeptide of 24 Amino acid is formed.
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What would happen if in a gene encoding a polypeptide of 50 amino acid...
Explanation:
In this question, we are given a gene that encodes a polypeptide of 50 amino acids. We need to determine the outcome if the 25th codon (UAU) is mutated to UAA.
Overview of the genetic code:
The genetic code is a set of rules that determine the correspondence between nucleotide triplets (codons) and amino acids in polypeptide chains. Each codon consists of three nucleotides, and there are 64 possible codons. Some codons code for the same amino acid, while others code for start or stop signals.
Effect of the mutation:
In the given question, the 25th codon is mutated from UAU to UAA. UAA is a stop codon, which means it signals the end of translation. When a stop codon is encountered during translation, the polypeptide chain is released, and the translation process terminates.
Consequences of the mutation:
When the 25th codon is mutated to UAA, it acts as a premature stop codon. This means that translation will terminate at this point, resulting in a shorter polypeptide chain. Since the original gene encoded a polypeptide of 50 amino acids, the mutation at the 25th codon will result in a polypeptide chain with only 24 amino acids.
Therefore, the correct answer is option 'b' - a polypeptide of 24 amino acids will be formed.
Note:
It is important to remember that mutations can have different effects depending on their location and the specific codon that is mutated. In this case, the mutation at the 25th codon introduced a premature stop codon, resulting in a shorter polypeptide chain. However, mutations can also lead to different outcomes such as amino acid substitutions, insertions, or deletions, which can have varying effects on protein structure and function.
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