#Question id: 23580
#Unit 13. Methods in Biology
#Question id: 13139
#Unit 10. Ecological Principles
#Question id: 23555
#General Aptitude
#Question id: 1238
#Unit 4. Cell Communication and Cell Signaling
Which of the following can lead to loss-of-heterozygosity in a tumor-suppressor gene?
a. deletion of the normal copy
b. non dysjunction during mitosis
c. somatic mutation of the normal copy
d. mitotic recombination between a wild-type and mutant allele
#Question id: 1520
#Unit 1. Molecules and their Interaction Relevant to Biology
Following statements are regarding to enzymatic processing of benzo(a)pyrene to a more potent mutagen and carcinogen.
A. Liver enzymes, particularly P-450 enzymes, modify benzo(a)pyrene in a series of reactions, producing 7,8-diol-9,10-epoxide, a highly potent mutagenic species that reacts with DNA primarily at the N2 atom of a guanine base.
B. The adduct, (+)-trans-anti-B(a)P-N2-dG, causes polymerase to insert an A rather than a C opposite the modified G base. Next time the DNA is replicated, a T will be inserted opposite the A, and the mutation will be complete.
C. Potent mutagen majorly causes conversion of guanine (G) to thymine (T) bases, a transition mutation.
D. When this potent mutagen applied to cultured bronchial epithelial cells, activated benzo(a)pyrene induces many mutations, including activating mutations at codons 175, 248, and 273 of the p53 gene.
Which of the following statements are correct?