Of all the mutations, which one would MOST LIKELY contribute to a rapid rate of extinction?

Let's first consider the major types of mutations possible in terms of the DNA sequence and the resulting amino acid sequence.

1. Missense mutation: change in 1 base pair of DNA results in change of 1 amino acid to another.

2. Nonsense mutation: change in 1 base pair of DNA results in change of 1 amino acid to a stop codon. This leads to an early termination of the original peptide sequence.

3. Insertion: addition...

Let's first consider the major types of mutations possible in terms of the DNA sequence and the resulting amino acid sequence.

1. Missense mutation: change in 1 base pair of DNA results in change of 1 amino acid to another.

2. Nonsense mutation: change in 1 base pair of DNA results in change of 1 amino acid to a stop codon. This leads to an early termination of the original peptide sequence.

3. Insertion: addition of base pairs of DNA (in groups of three) leads to the addition of amino acids to the peptide sequence.

4. Deletion: the deletion of base pairs of DNA (in groups of three) leads to deletions of amino acids from the peptide sequence.

5. Frameshift mutations: addition or deletion of base pairs of DNA (not in groups of 3) leads to shifting of coding frame. This leads to all the amino acids downstream from the mutation to be changed.

For all of the mutations listed above, there is potential for the resulting protein to no longer function like it should. This could have several potentially important implications. For example, this may make the protein perform its function better, leading to better survival/reproduction capabilities of the organism. These gain-of-function mutations may be beneficial to the fitness of the organism and this is the basis for evolution and natural selection. However, if the resulting mutant protein can no longer perform some important function in the organism (eg. the organism is no longer able to metabolize key nutrients), this will decrease the overall fitness and may contribute to the extinction of the species.

Of the mutations listed, frameshift mutations and nonsense mutations are most likely to have large effects and contribute to an extinction. This is because they have the biggest effects on the resulting peptide sequence, especially if the mutation occurs at the beginning of the coding sequence. Changing or losing all of the downstream coding sequence is likely to produce a protein that does not fold normally, or no longer has the necessary active site to catalyze its reaction.