A man inherited a chromosome with a deletion that removes a tumor-suppressor gene. The protein encoded by this gene normally functions in DNA damage repair. Which series of events would be most likely to lead to cancer?
A) Loss-of-heterozygosity of the tumor-suppressor gene followed by driver mutations in two different proto-oncogenes
B) A loss-of-function mutation in a proto-oncogene followed by a gain-of function mutation in a tumor-suppressor gene
C) Loss-of-heterozygosity of the tumor-suppressor gene followed by passenger mutations in several genes of unknown function
D) A gain-of-function mutation in a proto-oncogene followed by a chromosomal duplication of a region including a tumor-suppressor gene that functions the G1-to-S checkpoint
A) Loss-of-heterozygosity of the tumor-suppressor gene followed by driver mutations in two different proto-oncogenes
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Which of the following is not a property of homologous chromosomes?
A) They pair physically during prophase of meiosis I. B) They exchange genes by crossing over during meiosis. C) They carry alleles for the same genes at the same chromosomal position. D) Their centromeres are attached to each other during G2 of the cell cycle. E) They segregate to opposite poles at anaphase of meiosis I.
Mutations in promoter regions of a gene are most likely to _____
a. prevent mRNA from being synthesized b. trap mRNA inside the nucleus c. prevent mRNA from being recognized by the ribosome d. prevent mRNA from being post-transcriptionally modified e. alter the amino acid sequence
DNA that has wrapped around histones and is in a condensed form following interphase is called ________
A) chromatin B) nucleosomes C) chromosomes D) karyokinesis
Some codons are recognized by proteins, not by tRNAs.
Answer the following statement(s) true (T) or false (F)