Question

Which of the following statement(s) are correct with respect to mutation?
I. Insertion or deletion of 3 bases or its multiple does not change the reading frame from that point onwards
II. Mutation may occur due to the defects in the duplication of DNA
III. Mutations can be caused by certain chemicals

• A. Only III is correct
• B. I, II and III are correct
• C. II and III are correct
• D. Only I is correct

Answer 1

The correct option is B I, II and III are correct

Mutation is an alteration in the genetic material of a cell of a living organism that is more or less permanent. It may occur due to the defects in the duplication of DNA, certain chemicals, radiations etc.

The division of the polynucleotide molecule into sets of three consecutive nucleotides (triplet) that are non-overlapping is called the reading frame. When the triplets either specify amino acids or terminate protein synthesis, they are known as codons. Addition or deletion of nucleotides in count of 3 or its multiples does not affect the reading frame as there is direct addition or deletion of one codon consisting of three nucleotides.

Both environmental and genetic factors affect mutation rates. Ionizing radiation causes DNA damage (mutations).