Question

Scientists were examining the maize genome. They had two specimens: one control and one specimen that had undergone mutagenesis. They saw that the mutant specimen underwent a knockout caused by a nucleotide exchange in the DNA. When they compared gene sequences, they saw same number of nucleotide bases. Which type of mutation had most likely occurred? deletion insertion inversion substitution

Answer 1

The mutation observed in the maize, which involved a nucleotide exchange without a change in the total number of nucleotides, was a substitution mutation.

Step-by-step explanation:

The type of mutation that most likely occurred in the mutant maize specimen, where a nucleotide exchange happened but the number of nucleotides stayed the same, is a substitution mutation. A substitution mutation involves the replacement of one nucleotide with another, keeping the total number of nucleotides unchanged. This contrasts with insertion and deletion mutations, which respectively add to or remove nucleotides from the DNA sequence, and would have changed the overall number of nucleotides. Therefore, because the number of nucleotides in the gene sequence remained constant, an insertion, deletion, or inversion is not the type of mutation that took place here.

Answer 2

substitution

Step-by-step explanation:

A substitution is a point mutation where a nucleotide base (either adenine, guanine, thymine or cytosine) is replaced by a different base pair. In contrast to insertions or deletions, substitutions don't change the number of bases in the DNA sequence. Moreover, inversions are large genetic rearrangements where the genetic sequence is reversed. A substitution may have different effects: change a codon to another (changing the protein sequence when codons are translated into amino acids), produce a stop codon, cause synonymous mutations (i.e., neutral mutations that don't alter the amino acid sequence due to the degeneracy of the genetic code), etc.