Question

A mutation occurred that causes a change in mRNA sequence the mRNA codon UAC was replaced by the codon UAA. which statement describes the most likely outcome of the mutation

1.it will produce the same protein using a different set of codons
2.it will result in an incomplete protein that does not function properly
3.it will cause mRNA to attach a new amino acid chain during transcription
4.it will change the bonding pattern between the amino acids joining together

Answer 1

Answer: 2).it will result in an incomplete protein that does not function properly

Explanation: Mutations are permanent changes in the nucleotide sequence of a DNA. A mutated DNA sequence will give rise to an mRNA molecule with an altered nucleotide sequence and consequently lead to the synthesis of a nonfunctional protein with an altered amino acid sequence.

Amino acids are coded for by three nucleotide sequences called codons. There are 64 universal codons, 61 of them code for amino acids while 3 of them do not code for any amino acid and are called stop codons. Translation occurs when the ribosome encounters a stop codon in an mRNA.

When UAC codon is replaced by UAA codon in an mRNA sequence, protein synthesis will stop because UAC codes for tyrosine while UAA is a stop codon that do not code for an amino acid. This will result in an incomplete nonfunctional protein.