Question

Which of these mutational changes do you think will have the greatest deleterious effect on the function of a gene? Explain your answer.

a) insertion of a nucleotide at the end of the coding sequence

b) removal of a single nucleotide near the start of the coding sequence

c) deletion of three consecutive nucleotides in the middle of the coding region

d) deletion of four consecutive nucleotides in the middle of the coding region

e) replacement of one nucleotide by another in the middle of the coding region

Answer 1

ANSWER : - b.) removal of a single nucleotide near the start of the coding sequence.

From the above given statements, i think the removal of a single nucleotide near the start of the coding sequence, will have the greatest deleterious effect on the function of a gene, because, indels (insertions and deletions ) of one or two base pairs within the coding sequences have the greatest effect, because they will inevitably cause a framesshift mutation in the beginning of the sequence. The removal of a single consecutive nucleotide in the starting would change every amino acid along the rest of the sequence, resulting in most mutated result of all scenarios listed above. Only the addition of one of more three-base pair codon will keep the protein intact.

The insertion of a nucleotide at the end of the coding sequence do not cause such a deleterious effect on the function of gene as most of the sequence is already readed.

Deletion of three consequetive nucleotide in the middle of the coding region may also not have any much deleterious effect on the function of gene as it do not cause frameshift mutation.

Deletion of four consecutive nucleotides in the middle of the coding region may also not have much deleterious effecton the function of gene, as it may cause frameshift mutation, but most of the sequences is already readed.

Relpacement of one nucleotide by another is a substitution mutation and do not cause much deleterious effect on the function of gene.