AP Biology 12 Concept 1 continued: Analyzing components and reproduction cycles of viruses

1. AP Biology 12Concept 1 continued: Analyzing components and reproduction cycles of viruses Please refer to: Chapter 19 in Campbellpg 134-136 in Holtzclaw Practice Questions: Holtzclaw: #2,10 p.143,144 Campbell: #1,2 (19.1) p. 384#1, 2, 3, 4 (19.2) p. 390 #1,2,3,8 p. 395 ,

2. Learning Intentions • You must know: • The components of a virus • The differences between lytic and lysogenic cycles

3. Can you find the viruses? What are the viruses infecting?

4. What does this bacteriophage virus remind you of?

5. How were viruses first discovered? • Waaaaay smaller than bacteria! • Tobacco mosaic disease • How does this experiment support the idea of viruses?

6. Discuss: Are viruses alive or dead? Why? What defines a virus? What defines life?

7. Try This! • Which of the following is not a property of life shared by prokaryotic cells, eukaryotic cells, and viruses? • nucleic acids used to store hereditary information • order and complexity in arrangement of biological molecules • the ability to process energy through metabolic reactions • the capacity to evolve

8. Try This! • Which of the following is not a property of life shared by prokaryotic cells, eukaryotic cells, and viruses? • nucleic acids used to store hereditary information • order and complexity in arrangement of biological molecules • the ability to process energy through metabolic reactions • the capacity to evolve

9. Try This! Viruses:“a kind of borrowed life” • Classify each statement as TRUE or FALSE, and identify which statement supports the view of most biologists that viruses are nonliving. • Viruses are two-dimensional, rather than three-dimensional. • The viral genome may be single- or double-stranded. • Viruses are obligate intracellular parasites. • An isolated virus is unable to replicate its genes or regenerate ATP.

10. Try This! Viruses:“a kind of borrowed life” • Classify each statement as TRUE or FALSE, and identify which statement supports the view of most biologists that viruses are nonliving. • Viruses are two-dimensional, rather than three-dimensional. FALSE • The viral genome may be single- or double-stranded. TRUE • Viruses are obligate intracellular parasites. TRUE • An isolated virus is unable to replicate its genes or regenerate ATP.TRUE

11. What is a virus made of? • Genetic material: single or double stranded DNA or single or double stranded RNA • Protein shell: capsid • Some viruses also have viral envelopes from membrane of host cells

12. Compare the structure of these two viruses:

13. Compare the structure of these three viruses:

14. Try This! • Bacteriophages were grown in a medium containing radioactive sulfur (35S) and radioactive phosphorous (32P), which are incorporated into proteins and DNA, respectively. If these phages were used to infect a bacterial culture, which isotope would be detected within the infected bacteria? • 35S • 32P • both • neither

15. Try This! • Bacteriophages were grown in a medium containing radioactive sulfur (35S) and radioactive phosphorous (32P), which are incorporated into proteins and DNA, respectively. If these phages were used to infect a bacterial culture, which isotope would be detected within the infected bacteria? • 35S • 32P • both • neither

16. How do viruses replicate? • Overall: Simplified Viral Reproduction(Campbell Online)

17. How do viruses replicate? • Bacteriophage: Lytic vs lysogenic cycles (Campbell) (Campbell)

24. How does a virus replicate? • Retroviruses(Campbell)) • Use the enzyme reverse transcriptase • Example: HIV

25. Try This! • AZT is a nucleoside analog used to treat HIV infections. It is a thymine (T) nucleoside with an azide group instead of the hydroxyl group found in typical thymine nucleosides. Which step does AZT hamper in the reproductive cycle of the HIV virus? • entry into the cell • reverse transcription of DNA from RNA • transcription of RNA from proviral DNA • viral assembly within the cell

26. Try This! • AZT is a nucleoside analog used to treat HIV infections. It is a thymine (T) nucleoside with an azide group instead of the hydroxyl group found in typical thymine nucleosides. Which step does AZT hamper in the reproductive cycle of the HIV virus? • entry into the cell • reverse transcription of DNA from RNA • transcription of RNA from proviral DNA • viral assembly within the cell

27. Viroids and Prions: the really little guys • Viroids – circular RNA • Mostly affects plants • Prions – misfolded, infectious protein • Example: Mad Cow

28. Try This! • Identify all correct statements. • Unlike viruses, viroids do not encode proteins. • Unlike viruses, the genetic material of a viroid is RNA. • Unlike viruses, prions are infectious proteins. • Unlike viruses, prions do not include any nucleic acids.

29. Try This! • Identify all correct statements. • Unlike viruses, viroids do not encode proteins. • Unlike viruses, the genetic material of a viroid is RNA. • Unlike viruses, prions are infectious proteins. • Unlike viruses, prions do not include any nucleic acids.

30. Beautiful viral animation • Hepatitis C virus • Viral structures • Discovery Channel - Emerging Diseases(CD-Rom)

31. Learning Intentions • You must know: • The components of a virus • The differences between lytic and lysogenic cycles

32. Try These: • Explain how capsids and envelopes are formed • Distinguish between the lytic and lysogenic reproductive cycles • Explain why viruses are obligate intracellular parasites • Describe the reproductive cycle of an HIV retrovirus • Describe three processes that lead to the emergence of new diseases • Describe viroids and prions