Hypothetical indel mutations in the mtDNA cytochrome b gene of the Moose

Moose+0  5'-ttc ggt tct cta tta gga gtt tgc tta atc tta gaa atc -3'
             F   G   S   L   L   G   V   C   L   I   L   E   I

Moose+1  5'-ttc ggt tct cta tta Tgg agt ttg ctt aat ctt aga aat c -3'
             F   G   S   L   L   W   S   L   L   N   L   *
                               g
Moose-1  5'-ttc ggt tct cta ttaVgag ttt gct taa tct tag aaa tc -3'
             F   G   S   L   L   E   F   A   *

Moose+2  5'-ttc ggt tct cta tta TTg gag ttt gct taa tct tag aaa tc -3'
             F   G   S   L   L   L   E   F   A   *
                               gg
Moose-2  5'-ttc ggt tct cta ttaV agt ttg ctt aat ctt aga aat c -3'
             F   G   S   L   L    S   L   L   N   L   *

Moose+3  5'-ttc ggt tct cta tta tta gga gtt tgc tta atc tta gaa atc -3'
             F   G   S   L   L   L   G   V   C   L   I   L   E   I
                              gga
Moose-3  5'-ttc ggt tct cta ttaVgtt tgc tta atc tta gaa atc -3'
             F   G   S   L   L   V   C   L   I   L   E   I

    Line 1 shows the reading frame of standard Moose sequence, with 5th, 6th, & 7th triplets highlighted. 

    Lines 2 & 3 show a single-nucleotide insertion (T) or deletion (g) at the sixth triplet.
    Lines 4 & 5 show a double-nucleotide insertion (TT) or deletion (gg) at the sixth triplet.
    Lines 6 & 7 show a triplet insertion (TTA) or deletion (gga) of the sixth triplet.

The insertion or deletion of a single nucleotide is called an indel, because the direction of the change cannot (usually) be inferred directly from the sequences compared.

An indel of 1 or 2 nucleotides alters the reading frame, such that the polypeptide sequence is altered, and a premature stop triplet is generated at random

An indel of 3 nucleotides leaves the reading frames unchanged, such that a single amino acid is inserted or deleted.

Only the sense DNA strand is shown. Amino acids are given in the single-letter code: the mtDNA code is slightly different from the "universal" code.