Question

Which of the following would result in a protein not being produced at all?

A. the deletion of a promoter from a gene

B. an intron not being spliced from the mRNA

C. a point mutation changing a phenylalanine to a lysine in the third exon

D. a mutation in the stop codon

Answer 1

Option A

Promoter is a region on DNA where RNA polymerase binds to initiate the transcription of downstream genes. If promoter region is deleted, then there will be no transcription and hence no translation of the gene. It is because, the Messenger RNA formed after transcription is the template for the synthesis of proteins during translation. If transcription will not take place, then messenger RNA will not be formed and therefore proteins will also not be formed in the cell.

Second option is incorrect because if an intron is not spliced out from the Messenger RNA, then it will be present in the final protein product.

Third option is incorrect because. Mutation will lead to a change in one or more amino acid of the protein, but protein will be formed.

Last option is incorrect because it stop codon is mutated, then readthrough mutation will occur resulting in the formation of a peptide which will be longer than the normal one.

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