21. Which of the following is an example of a processive enzyme?
(A) DNA polymerase I
(B) DNA polymerase III
(C)DNA ligase
(D) Okazaki fragments

17. According to Chargaff's rule, if the DNA of a species contains 20% adenine, what percent of guanine will it contain? (A) 20% (B) 30% (C)50% (D) 75%

18. The first group of researchers to correctly identify the double-helix structure of DNA were _____(A) McClintock and Franklin (B) Hershey and Chase (C)Pauling and Avery (D) Watson and Crick

19. You have discovered a strain of E. coli that grows very slowly-the generation time is nearly 12 hours compared to the normal 20-30 minutes. Upon further investigation, you find a mutation in the DNA polymerase III gene. What subunit of the holoenzyme, does this mutation affect the most. (A) α (B) β (C)γ (D) ψ

20. Okazaki fragments do which of the following? (A) assist in forming the replication fork (B) bind to the oriC region (C)assist in the synthesis of DNA from the lagging strand (D) reform the double-helix following replication

22. Most eukaryotic genes are collinear. (A) True (B) False (C)Because they are driven by a promoter (D) B and C are right

23. An R loop experiment was performed on two different mRNA's. The first showed one R loop, while the second showed two R loops separated by a region of double-stranded DNA. What is the composition of these two mRNA's? (A) The first contains no introns and the second two introns (B) The first contains no introns and the second one intron (C)The first contains one intron and the second two introns (D) The first contains two introns and the second one intron

24. What enables the splicing of group I and II introns? (A) spliceosomes (B) ribozymes (C)snRNA (D) poly-A tail

25. Where does mRNA/tRNA codon-anticodon recognition take place? (A) 30S (B) 40S (C)50S (D) the surface between the two ribosomal subunits

26. With regard to Chapeville's experiment, what could not be the radioactive element used to label cysteine? (A) 15N (B) 35S (C)C (D) H

27. If a bacteria is placed in an environment that contains both glucose and lactose, the regulation of the lac operon will allow which nutrient to be processed first? (A) glucose (B) lactose (C)Both will be processed equally (D) Neither will be processed in this environment