Frameshift mutation occurs when :

Options

A. base is deleted
B. base is deleted or added
C. base is added
D. anticodons are not present .

Answer

B

Explanation

Framshift mutation occurs when one or more nucleotides are either added to deleted from DNA. The result of such mutation is nonfunctioning of protein because the sequence of codons is altered . Example of framshift mutation due to deletion.
Original ( wild type ) message or reading frame
CAT GAT CAT GAT CAt GAT CAT
Deletion
CAT GAT ATG ATC ATG ATC AT
Message out of frame