A frameshift mutation is a type of gene mutation that occurs when nucleotides are inserted or deleted from the DNA sequence, changing the reading frame of the genetic code.
Explanation
Genes are read in groups of three nucleotides called codons, and each codon codes for one amino acid.
If one or two nucleotides are added or removed (not a multiple of three), the entire reading frame shifts — this changes every codon after the mutation point.
Example
Original sequence:AUG-CGA-UUC-GAA → (codes for specific amino acids)
If one base is deleted:AUG-GAU-UCG-AA... → now the codons are read differently, leading to wrong amino acids.
Effects on Gene Function
- Alters amino acid sequence — produces a completely different protein.
- Creates premature stop codons — resulting in a truncated (short, incomplete) protein.
- Loss of protein function — the protein may be nonfunctional or harmful.
In Plants
Frameshift mutations can cause:
- Loss of important enzymes in metabolic pathways.
- Changes in pigment production (affecting flower or leaf color).
- Altered resistance to diseases or stress.
In summary:
A frameshift mutation shifts the genetic reading frame by insertion or deletion of nucleotides, usually resulting in a defective or nonfunctional protein.