Changes in DNA can Affect the Phenotype
Insertions
- A new base is randomly inserted into the DNA sequence
- An insertion mutation changes the amino acid that would have been coded for by the group of three bases in which the mutation occurs
- Remember – every group of three bases in a DNA sequence codes for an amino acid
- An insertion mutation also has a knock-on effect by changing the groups of three bases further on in the DNA sequence
An example of an insertion mutation
Deletions
- A base is randomly deleted from the DNA sequence
- Like an insertion mutation, a deletion mutation changes the amino acid that would have been coded for by the group of three bases in which the mutation occurs
- Like an insertion mutation, a deletion mutation also has a knock-on effect by changing the groups of three bases further on in the DNA sequence
Substitutions
- A base in the DNA sequence is randomly swapped for a different base
- Unlike an insertion or deletion mutation, a substitution mutation will only change the amino acid for the group of three bases in which the mutation occurs; it will not have a knock-on effect
An example of a substitution mutation
