DNA: TTA CGC AAC TGG CTA ATT mRNA: AAU GCG UGA CCG AUU AAC

Identify the type of mutation that occurred in the sequence above and evaluate the significance of these changes. (Will it have any problems in protein synthesis?)

Hint: 1st determine if it was copied to mRNA correctly. When you find the error, that is the mutation. 2nd use the chart if a different amino acid is created, this will determine if it will affect protein synthesis.

See the answer below.

Explanation:

The correct mRNA sequence from the DNA according to the base pairing rule should be:

                       AAU GCG UUG ACC GAU UAA

Instead of:

                        AAU GCG UGA CCG AUU AAC

This thus means that some of the nucleotide bases have been wrongly substituted.

The most important change is the codon 'UUG' becoming 'UGA', while the former codes for the amino acid leucine, the latter represents a stop codon. A  stop codon will result in a non-functional or defective protein.

Hence, the type of mutation is nonsense mutation which results in a sudden cessation of protein synthesis as a result of a codon being prematurely changed to a stop codon.

The significance of this kind of mutation is that a defective on non-functional protein will result which will have a serious phenotypic implication in organisms.

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