n your lab you are studying the genome of venomous rattlesnakes to find the gene which codes for their venom glands. You have two rattlesnakes, one rattlesnake has a mutation but can still produce venom. You compare his DNA to a normal rattlesnake. What type of mutation has occurred? Normal: AATCGCTACGCACGTCAG Mutated: TATCGCTACGCACGTCAG

Mutation is any change, whether small or big, in the nucleotide sequence of a gene (DNA). Mutation occurs from time to time in an organism either by a mistake during DNA replication or induced by a mutagen (mutation-causing substance). Mutation can be of different types depending on the effect on the mutant.

In this case of comparing the DNA sequence two rattle snakes, the sequences of the two snakes are:

Normal: AATCGCTACGCACGTCAG

Mutated: TATCGCTACGCACGTCAG

By carefully observing the two DNA sequences, one would realize that the only difference in the two sequences is the first nucleotide base. That is, in the normal sequence, th first base is Adenine (A) while in the mutated sequence, the first base is Thymine (T).

This type of mutation that involves only one nucleotide base is called POINT MUTATION. It can also be noticed that base "A" was changed "T". Hence, this is a type of SUBSTITUTION MUTATION because a single base was replaced by another in the sequence.