Q7.1 Five strains of E. coli containing base-substitution c. rom what you can in
ID: 88821 • Letter: Q
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Q7.1 Five strains of E. coli containing base-substitution c. rom what you can infer of the nucleotide sequence mutations that affect the tryptophan synthetase A in the wild-type gene, indicate, for the codons speci lying amino acids 48, 210, 233, and 234, whether polypeptide have been isolated. Figure 7.A shows the a nonsense mutant could be generated by a single changes produced in the protein itself in the indicated nucleotide substitution in the gene. mutant strains. In addition, A23 can be further mutated to insert lle, Thr, Ser, or the wild-type Gly into positionExplanation / Answer
To start with what is base substitution mutation:
Base substitution mutation is a type of mutation which involves replacement of a single nucleotide base with another in DNA or RNA molecule. If one purine{ A or G} or pyrimidine {C or T} is replaced by the other it is known as a transition but if purine is replaced by pyrimidine or vice versa it is transversing. When this type of mutation occurs in non coding sequences often does not alter amino acid sequence during translation. But when this mutation occurs in the promoter sequences of a gene may result in structure and function of a protein product.
Yes a nonsense mutant could be generated by a single nucleotide substitution in the gene as the new nucleotide changed a codon that specified an amino acid to one of the stop codons. In this particular example A46 mutant of E.coli has got converted to amino acid which is coded by UAA which is a stop codon.
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