Exam 2 Key - Spring 2008 A#: Please see us if you have any questions!

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1 Page 1 of 5 Exam 2 Key - Spring 2008 A#: Please see us if you have any questions! 1. A mutation in which parts of two nonhomologous chromosomes change places is called a(n) A. translocation. B. transition. C. transversion. D. insertion. E. deletion. 2. Thymine dimers are caused by A. X-rays. B. free radicals such as oxygen. C. EMS or NSG. D. depurination. E. UV light. 3. The consequence to a bacterial cell of a mutation that inactivated the enzyme that methylates the A of the sequence GATC in newly made DNA would be A. failure to carry out replication. B. failure to correct thymine dimers. C. failure to distinguish old and new DNA during mismatch repair. D. inactivation of certain metabolic genes. E. decrease in the mutation rate. 4. Consider the pathway for the synthesis of the amino acid arginine in Neurospora : Mutant strains of Neurospora are grown in minimal media supplements as follows. Each mutant strain carries only a single mutation. Growth is shown by (+), no growth is shown by (o).

2 Page 2 of 5 Indicate the correct pairing: mutant strain / defective gene. A. strain a / ARG-F B. strain a / ARG-H C. strain b / ARG-F D. strain c / ARG-E E. strain c / ARG-F 5. In a PCR reaction tube, the following reagents are required for successful amplification of a target region of DNA: A. DNA template, dideoxynucleotides, DNA polymerase, two primers B. DNA template, deoxynucletides, DNA polymerase, two primers C. DNA template, deoxynucleotides, DNA polymerase, one primer D. DNA template, deoxynucleotides, dideoxynucleotides, DNA polymerase, two primers 6. The sequences within mrna that are spliced out (removed) are called A. extremes. B. exons. C. inclusions. D. introns. 7. Transcription occurs in the and translation occurs in the of prokaryotic cells. A. nucleus; cytoplasm B. cytoplasm; nucleus C. nucleus; nucleus D. cytoplasm; cytoplasm 8. Ribosomes are composed of A. trna and protein. B. mrna and protein. C. rrna and protein. D. only proteins folded together. E. rrna and mrna 9. Aminoacyl-tRNA synthetase is the enzyme that A. folds trna molecules into their proper configuration.

3 Page 3 of 5 B. causes trna molecules to bind to the aminoacyl site of a ribosome. C. produces trna by "reading" DNA molecules. D. adds the appropriate amino acid to an uncharged trna. 10. Molecular cloning uses ampicillin specifically to: A. determine which cells are carrying the plasmid with the insert B. determine which cells are competent C. determine which cells are carrying the plasmid D. prevent the growth of unwanted fungus E. interrupt the Lac Z gene 11. In Sanger (enzymatic extension) sequencing, what causes DNA synthesis to terminate at a specific base? A. chemicals that cleave DNA after particular bases B. fluorescent chemicals C. nucleotide triphosphates that lack a base D. nucleotide triphosphates that lack a 3 prime hydroxyl group E. nucleosides that lack a 5' phosphate 12. Where do restriction enzymes come from, and what is their normal physiological function? A. Phage l produces them, and they replicate viral DNA. B. Phage l produces them and they confer antibiotic resistance. C. They are yeast DNA replication enzymes. D. Bacteria produce them to protect against viral invasion. E. They are bacterial DNA replication enzymes. 13. What DNA sequence information is not present in a cdna? A. the promoter B. the introns C. the exons D. the 3' untranslated region E. the promoter and the introns 14. The events that occur during amplification via PCR occur in the following order: A. Anneal, Denature, Repeat, Elongate B. Denature, Elongate, Anneal Repeat C. Anneal, Denature, Elongate Repeat D. Denature. Anneal, Elongate, Repeat E. Elongate, Anneal, Denature Repeat 15. A hairpin loop in an mrna functions in

4 Page 4 of 5 A. initiating translation B. terminating transcription C. terminating translation. D. intron splicing E. exon splicing 16. The function of DNA polymerases 3 prime to 5 prime exonuclease activity is to A. add RNA nucleotides to the growing mrna transcript B. separate the two DNA strands giving the polymerase access to the template strand C. relax supercoiling that occurs as the DNA is unwound D. terminate transcription upon reading a stop codon E. recognize and excise mismatched bases 17. In eukaryotes, mrna is modified after transcription by: A. removal of fmet B. removal of 5 prime cap and poly A tail C. addition of 5 prime cap and poly A tail D. Addition of 5 prime cap and removal of poly A tail E. Removal of 5 prime cap and addition of poly A tail 18. A peptide bond is a: A. single bond between the carboxyl group of one amino acid and the amino group of another amino acid B. single bond between the R group of one amino acid and the carboxyl group of another amino acid C. covalent bond between the amino groups of two amino acids D. covalent bond between a sugar and phosphate group E. ionic bond between two carboxyl groups 19. Which of the following is not true of DNA? A. It is acidic. B. It contains deoxyribose. C. It is found in cell nuclei. D. It contains phosphate. E. It contains proteins. 20. The ratio of is 1:1. A. guanine to adenine B. adenine to thymine C. cytosine to adenine D. uracil to cytosine 21. bonds are responsible for the chemical affinity between A and T (or G and C) nucleotides. A. Ionic B. Covalent C. Hydrogen D. Electro-ionic

5 Page 5 of DNA replication occurs through a process. A. conservative B. semiconservative C. dispersive D. transferal 23. The group of enzymes able to relax supercoils in DNA are called A. primases. B. helicases. C. topoisomerases. D. telomeres. E. ligases. 24. The complementary sequence of 5' AATTCGCTTA 3' is A. 5' AATTCGCTTA 3'. B. 3' AATTCGCTTA 5'. C. 5' TTAAGCGAAT 3'. D. 5' TAAGCGAATT 3'. E. 3' TAAGCGAATT 5'. 25. The Hershey and Chase experiment proved that A. chromosomes carried the genetic material B. DNA and not protein was the genetic material C. codons consisted of 3 nucleotides that coded for an amino acid D. trnas could recognize multiple codons E. recombination occurred at chiasmata Return to Home page