Bio Practice Exam 28 Questions with Verified Answers,100% CORRECT, Exams of Nursing

Download Bio Practice Exam 28 Questions with Verified Answers,100% CORRECT and more Exams Nursing in PDF only on Docsity! Bio Practice Exam 28 Questions with Verified Answers Why did DNA evolve to be the carrier of genetic information in cells as opposed to RNA? - CORRECT ANSWER the hydrogen at the 2' position in the deoxyribose of DNA makes it more stable than RNA In the mismatch repair process, enzyme complexes replace bases that were incorrectly inserted into the newly synthesized DNA strand. To function, they must be able to distinguish between the parent DNA strand and the new strand. How is this accomplished? - CORRECT ANSWER the parent strand is methylated suppose an experimenter becomes proficient with a technique that allows her to move DNA sequences within a prokaryotic genome. She decides to use this technique to study the lac operon. If she leaves the promoter in place but moves the operator downstream to the far end of the operon past the three structural genes, which of the following would likely occur when the cell is exposed to lactose? a) The operon will never be transcribed b) The repressor protein will no longer be produced c) The structural genes will be transcribed continuously - CORRECT ANSWER c. the structural genes will be transcribed continuously. If she moves (reference above) the repressor gene (lac I), along with its promoter, to a position at some several thousand base pairs upstream from its normal position, which will you expect to occur? - CORRECT ANSWER The lac operon will function normally Under which conditions will the lac Z gene be expressed at the highest rate? - CORRECT ANSWER no glucose, high lactose The error rate in the human genome is 3.4 bases per round of replication. All the following contribute to error except? a. DNA polymerase b. homologous recombination c. polyadenylation d. base excision pair - CORRECT ANSWER c. polyadenylation In humans, xeroderma pigmentosum (XP) is a disorder of the nucleotide excision repair mechanism. These individuals are unable to repair DNA damage caused by ultraviolet light. Multiple basal cell carcinomas and other skin malignancies frequently occur at a young age in those with XP. Which of the following are the most prominent types of mutations in individuals suffering from XP? a. telomere shortening b. thymine dimers c. mismatch repair d. methylation of purines e. all of these - CORRECT ANSWER b. thymine dimers In a specific DNA sequencing method, di-deoxy-nucleoside- triphosphates (ddNTP's) are involved to produce replicated DNA strands of varying lengths. Once a ddNTP is incorporated into the growing strand of DNA, replication is stopped. Why does the incorporation of a ddNTP in a newly synthesized strand of DNA cease replication? - CORRECT ANSWER A ddNTP has no 3' hydroxyl group available to form a phosphodiester bond with the phosphate of the next incoming dNTP. For transcription in eukaryotes, either strand of double-stranded DNA may be the template strand. What determines which strand is the template strand? - CORRECT ANSWER The base sequence of the promoter (TATA box) Which best describes the characteristics and function of a 5'-methyl-guanosine cap of a eukaryotic mRNA? - CORRECT ANSWER A methylated purine that is added, to the first nucleotide of the transcript to protect the mRNA from degradation by nucleases in the cytoplasm. What would the most likely result of a prokaryotic species that develops a mutation that allows it to encode for the enzyme telomerase? a. The prokaryotic species would likely have a longer life-span due to the fact that its telomeres do not ever shorten. b. The prokaryotic species would have the capability to divide more rapidly because telomerase speeds the last step of DNA replication. c. There would be no effect on a prokaryote if it developed this mutation. - CORRECT ANSWER c. There would be no effect on a prokaryote if it developed this mutation.