AP Biology Name _________________________
Chapter 18 Guided Reading Assignment
1. How small are viruses?

2. What kind of nucleic acids are the viral genomes made of?

3. What is the name for a protein shell enclosing the viral genome?

4. What are the subunits of capsids?

5. What are viral envelopes and what is their function?

6. Where are the most complex capsids found?

7. Define host range.

8. List the full steps of the simplified viral reproductive cycle.

9. What kind of phage only reproduces by a lytic cycle?

10. How do bacteria defend themselves against phages?

11. What is the phage reproductive cycle that replicates the phage genome without destroying the host?

12. What are phages called that care capable of using both modes of reproduction?

13. What is a prophage?

14. What is the use of a viral envelope in animal viruses?

15. Does this reproductive cycle kill the host cell?

16. What are retroviruses and how do they use reverse transcriptase?

17. Describe the reproductive cycle of an enveloped RNA virus.

18. Describe the reproductive cycle of HIV, a retrovirus.

19. Is it believed that viruses evolved before or after the first cells appeared and what evidence is used to support the idea?

20. What are vaccines?

21. What are the three processes that contribute to the emergence of viral diseases?

22. What are viroids?

23. Define prions.

24. How is the DNA arranged in the nucleoid region of the bacterial genome?

25. What is a plasmid?

26. Why do mutations make such a large contribution to bacterial genetic variation as compared to humans?

27. Explain the experiment and the results that demonstrated evidence of genetic recombination in bacteria.

28. What is the process of alteration of a bacterial cell’s genotype by the uptake of naked, foreign DNA from the surrounding environment?

29. What famous experiment in the previous unit described this process?

30. Define transduction.

31. List the generalized steps of transduction.

32. What is the process of direct transfer of genetic material between two bacterial cells that are temporarily joined?

33. What is special about the F plasmid?

34. What is an episome?

35. What are R plasmids and why are these a problem to humans?

36. How does this relate to natural selection?

37. Define transposable elements.

38. What is the key advantage of grouping genes of related function in to one transcription unit?

39. What is this “switch” called?

40. Where is an operator positioned?

41. What does the operator control?

42. What is the name for the operator, promoter, and the genes they control?

43. What can happen if the trp operan is turned “on”?

44. What turns the “switch” off?

45. How does a repressor work?

46. What are the two methods of negative gene regulation?

47. Why is the trp operan considered repressible?

48. What is the definition of an inducible operan?

49. What does the inducer do?

50. Why are repressible enzymes generally associated with anabolic pathways and how is this an advantage to the organism?

51. How does positive gene regulation work?

52. We stated in the beginning of the year that negative feedback has an on/off switch and positive feedback can only amplify the response – how does this statement connect with negative and positive gene regulation?