Question

DNA mutations that do cause any functional change in the protein product are known as
(a) Nonsense mutations
(b) Missense mutations
(c) Deletion mutations
(d) Silent Mutations

Answer 1

Hint: These are the kind of mutations in DNA that don't have an observable effect on the organism's phenotype. They're a specific form of neutral mutation, they do not change the amino acid that gets put in.

Complete step by step answer:
A point mutation during a sequence of DNA causing premature stop codon within the transcribing mRNA is understood as a nonsense mutation. It leads to premature termination of translation and therefore the resulting shortened protein is either non- functional or less functional which makes option A wrong. A point mutation that is able to change a codon specifying a unique amino acid is named as a missense mutation. It can alter the protein activity to the severity which will cause a disease like sickle cell anemia, option B is wrong. Removal of 1 or more nucleotide bases to the DNA segment is understood as deletion. It can remove 1 to several nucleotide bases from the DNA leading to shortening of the encoded proteins which are mostly non- functional which makes option C wrong. A mutation causing no change in the amino acid and hence, no effect on the function of the protein is called the silent mutation.
So, the correct answer is, ‘Silent Mutations.’

Additional Information: The mutation is also seen in chromosomes where segments of genes are disturbed. These are called chromosomal aberrations or abnormalities and consist of the following types.
- Inversion: Part of the gene is inverted and attached again.
- Deletion: Part of the gene is deleted.
- Duplication: Part of the gene or the entire chromosome is duplicated.
- Translocation: Part of the gene from one chromosome is attached to a different chromosome.

Note: Mutation and recombination cause change in the genetic material of an organism. This variation in DNA is what leads to evolution over time. Chromosomal aberrations are seen in cancer cells. The major cause of mutations is errors that happen during DNA replication and recombination.
Mutagens are substances that induce mutation in the genome and include UV rays, chemotherapeutic drugs, etc.