Download Student Virus Notes

AP Biology 12
Concept 1 continued:
Analyzing components & reproduction cycles of viruses
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You must know:
o
o
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The components of a virus
The differences between lytic and lysogenic cycles
How were viruses first discovered?
How big are viruses?
What is a virus made of?
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Genetic material: single or double stranded _______ or single or double stranded _______
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Protein shell: __________________
Some viruses also have ____________________from membrane of host cells
Try This!
1. Which of the following is not a property of life shared by prokaryotic cells, eukaryotic cells, and viruses?
A.
nucleic acids used to store hereditary information
B.
order and complexity in arrangement of biological molecules
C.
D.
the ability to process energy through metabolic reactions
the capacity to evolve
2. Classify each statement as TRUE or FALSE, and identify which statement supports the view of most
biologists that viruses are nonliving.
A.
Viruses are two-dimensional, rather than three-dimensional.
B.
The viral genome may be single- or double-stranded.
C.
Viruses are obligate intracellular parasites.
D.
An isolated virus is unable to replicate its genes or regenerate ATP.
3. 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?
A.
35
B.
32
C.
D.
both
neither
S
P
How do viruses replicate?
The Lytic Cycle
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Ends in ________________of host cell by rupturing (lysis)
Bacteriophage injects its DNA into host and takes over ______________________of host to synthesis
new copies of virus (DNA and protein coats)
They self-assemble and then release.
Lysogenic Cycle
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Bacteriophage DNA becomes incorporated into the ____________cell’s DNA and is replicated along
with the host cell’s genetic information
Viral DNA is called ______________________
Sometimes, prophage will enter the lytic cycle.
Retroviruses
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
Use the enzyme reverse transcriptase
Example: ____________________
Try This!
4. AZT is a nucleoside analog used to treat HIV infections. It is a thymine (T) nucleotide 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?
A.
entry into the cell
B.
reverse transcription of DNA from RNA
C.
D.
transcription of RNA from proviral DNA
viral assembly within the cell
Viroids and Prions: the really little guys
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Viroids – circular RNA
o
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Mostly affects __________________
Prions –__________________, infectious protein
o Example: Mad Cow
Try This!
5. Identify all correct statements.
A.
Unlike viruses, viroids do not encode proteins.
B.
Unlike viruses, the genetic material of a viroid is RNA.
C.
D.
Unlike viruses, prions are infectious proteins.
Unlike viruses, prions do not include any nucleic acids.
Can you do these?
1. Explain how capsids and envelopes are formed
2. Distinguish between the lytic and lysogenic reproductive cycles
3. Explain why viruses are obligate intracellular parasites
4. Describe the reproductive cycle of an HIV retrovirus
5. Describe three processes that lead to the emergence of new diseases
6. Describe viroids and prions