Name one mutagenic agent.

Name one mutagenic agent.

• A. Colchicine
• B. Water
• C. Vitamin C
• D. Ultraviolet light

Answer: (D)

DNA mutagens are factors that increase the rate of mutations by damaging DNA. Ultraviolet light is a classic physical mutagen because it directly alters DNA bases. It causes covalent bonds to form between adjacent pyrimidines, usually thymines, creating thymine (and other pyrimidine) dimers. These dimers distort the DNA helix and block proper base pairing during replication. If the cell’s repair systems, such as nucleotide excision repair, fix these lesions correctly, mutations are avoided; if not repaired or repaired inaccurately, mistakes during replication can lead to mutations. Colchicine disrupts microtubule formation and blocks chromosome separation during cell division, but it doesn’t change the DNA sequence itself. Water does not damage DNA in a mutagenic way under normal conditions. Vitamin C is an antioxidant and is not considered a mutagen in typical contexts.

DNA mutagens are factors that increase the rate of mutations by damaging DNA. Ultraviolet light is a classic physical mutagen because it directly alters DNA bases. It causes covalent bonds to form between adjacent pyrimidines, usually thymines, creating thymine (and other pyrimidine) dimers. These dimers distort the DNA helix and block proper base pairing during replication. If the cell’s repair systems, such as nucleotide excision repair, fix these lesions correctly, mutations are avoided; if not repaired or repaired inaccurately, mistakes during replication can lead to mutations.

Colchicine disrupts microtubule formation and blocks chromosome separation during cell division, but it doesn’t change the DNA sequence itself. Water does not damage DNA in a mutagenic way under normal conditions. Vitamin C is an antioxidant and is not considered a mutagen in typical contexts.