Final answer:
Insertions or deletions during VDJ recombination are defined as extra or fewer DNA and nucleotide sequences. These can result in frameshift mutations, with the insertion of three nucleotides being typically less harmful than one because it maintains the reading frame for codons downstream.
Step-by-step explanation:
Insertions or deletions during VDJ recombination are defined as extra or fewer DNA and nucleotide sequences. This can lead to frameshift mutations, where the insertion or deletion of nucleotides may result in a shift in the reading frame of the gene or the insertion of a stop codon. A frameshift mutation that results in the insertion of three nucleotides is often less deleterious than a mutation that results in the insertion of one nucleotide because the insertion of three nucleotides does not alter the reading frame as seriously as the insertion of one. This is because the genetic code is read in sets of three nucleotides, called codons, that correspond to amino acids. An insertion or deletion that is not a multiple of three will alter the entire reading frame downstream, thus changing every subsequent codon and potentially leading to a nonfunctional protein.