STB1033_Mutation

Mutations are errors in DNA that

• are always harmful
• only occur in the presence of carcinogens
• increase tumour growth
• occur spontaneously at a low rate

Which listed below is the base modifying agent ?

• 5-bromouracil (5BU)
• Methylmethane sulfonate (MMS)
• Nitrous acid (HNO₂)
• Sulfuric acid (H₂SO₄)

Spontaneous mutations are the result of exposure to mutagens. 

• True
• False

What is nonsense mutation?

• change a codon to a stop codon, resulting in premature termination of translation and a truncated protein
• a base-pair change resulting in a different mRNA codon, and therefore a different amino acid in the protein
• conversion of a purine-pyrimidine pair to a pyrimidine-purine pair 
• conversion of a purine-pyrimidine pair to the other purine-pyrimidine pair 

Mutation is quantified by it's rate and frequency.

• True
• False

What is reverse mutation?

• change of genotype from mutant to wild-type or partially wild-type
• change of genotype from wild type to mutant
• change in a codon, resulting in amino acid substitution 
• mutant codon encodes the same amino acid as the wild-type gene

Deamination removes the purine (A or G) from DNA by breaking the bond with its deoxyribose in the backbone

• True
• False

Statement listed below explains ionizing radiation EXCEPT:  

• Ionizing radiation is the leading cause of human gross chromosomal mutations
• Ions can break covalent bonds, including those in the DNA sugar-phosphate backbone
• Ionizing radiation kills cells at high doses, and lower doses produce point mutations
• Ionizing radiation has a decreasing effect

UV in certain wavelength is strongly absorbed by purines and pyrimidines, forming abnormal chemical bonds. What is the range?

• 254-260 nm
• 246-250 nm
• 256- 270 nm
• 240-260 nm

Which listed below are the chemical mutagens?
I: base analogs
II: base modifying agents
III: mutagenic analogs
IV: intercalating agents

• I & II
• I, II & III
• I, II & IV
• All above