17 Bacteria and Viruses
ENCOUNTER THE PHENOMENON
Write the Encounter the Phenomenon question for this module.
Use the “What I Know” column to list the things you know about the Encounter the Phenomenon
question. Then list the questions you have about the Encounter the Phenomenon question in the
“What I Want to Find Out” column. As you read the module, fill in the “What I Learned” column.
W
What I Want to Find Out
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K
What I Know
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L
What I Learned
Bacteria and Viruses
1 Bacteria
REVIEW
VOCABULARY
prokaryotic cell
Recall the definition of the Review Vocabulary term.
prokaryotic cell
NEW VOCABULARY
Use your book to define each term.
bacteria
bacteria
nucleoid
capsule
pilus
binary fission
nucleoid
capsule
pilus
conjugation
endospore
binary fission
conjugation
endospore
1.
2.
3.
Model a prokaryotic cell and label its structures.
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Summarize three general environments where archaea live, and give
one example of each environment.
1 Bacteria (continued)
Get It?
flagella.
Explain the difference between prokaryotic and eukaryotic
Identify each prokaryote shape below with its scientific name.
Compare prokaryote reproduction by completing the table below.
Reproduction
Method
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Process
Result
Compare prokaryotes by describing how each group below obtains
energy for cellular respiration.
Saprotrophs:
Photoautotrophs:
Chemoautotrophs:
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1 Bacteria (continued)
Get It? Summarize the importance of photosynthesis and cellular
metabolism in bacterial metabolism.
Identify two bacterial survival mechanisms and describe the
advantages of each mechanism.
Mechanism
Survival Advantages
Get It?
Explain how mutations can help a population of bacteria
develop new adaptations in response to a change in the environment.
Bacteria
are
helpful
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List five ways that bacteria are helpful to humans.
1 Bacteria (continued)
CHECK YOUR PROGRESS
1. Diagram a bacterium.
2. Discuss possible rationales that taxonomists might have used when deciding to
group prokaryotes into two distinct domains instead of in one group.
3. Explain survival mechanisms of bacteria at both the individual and population levels.
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4. List three ways bacteria are beneficial to humans.
5. Analyze why it is more difficult for biologists to understand the diversity in
prokaryotes as compared to plants or animals.
6. Imagine that today at 1 P.M., a single Salmonella bacterial cell landed on potato
salad sitting on your kitchen counter. Assuming optimal conditions for bacterial
growth, how many bacterial cells will be present at 3 P.M. today?
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Bacteria and Viruses
2 Viruses and Prions
REVIEW
VOCABULARY
protein
NEW VOCABULARY
virus
capsid
lytic cycle
lysogenic cycle
retrovirus
prion
Recall the definition of the Review Vocabulary term.
protein
Use the new vocabulary terms in the left column to complete the
following paragraph.
A
is genetic material within a protein coat, but
it has no organelles or other characteristics of life. The genetic
material lies inside its
the
, or outer layer of protein. In
viral genes instruct the host cell to make
many copies of the viral RNA or DNA. Some viruses replicate in a
, in which the viral DNA integrates into a host
chromosome and lies dormant for some time. A
,
such as the HIV virus, contains RNA instead of DNA. Mutation in
the genes of a normal protein called a
is responsible
for diseases such as “mad cow.”
ACADEMIC
VOCABULARY
Define widespread to show its scientific meaning.
widespread
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238
2 Viruses and Prions (continued)
Sketch t he general structure of a virus.
Synthesize why many viruses cannot pass from one species to
another.
Label steps A, B, C, D, and E of a lytic cycle in the figure below. Use
the following terms.
• Assembly
•Attachment
• Lysis and Release
• Replication
Bacteriophage
Nucleic
acid
• Entry
Bacterial DNA
Bacterial
host cell
B
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A
The bacteriophage
injects its nucleic acid
into the bacterial cell.
E
The host cell breaks open and
releases new virus particles.
C
D
New virus
particles are
assembled.
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C18-05C-873043-BO-A
The host’s
metabolic
machinery makes
viral nucleic acid
and proteins.
2 Viruses and Prions (continued)
Sequence the steps of a lysogenic cycle.
Viral DNA integrates into a chromosome of a host cell.
Evaluate and discuss the role of reverse transcriptase in the
replication cycle of HIV.
Summarize information about prions by completing the table.
What causes a prion to become
harmful?
How might humans contract a
prion-caused disease?
What is the result of prion
infection?
SUMMARIZE
Conclude whether viruses that replicate by the lytic cycle or the lysogenic cycle are more
dangerous. Explain your reasoning.
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What is a prion?
2 Viruses and Prions (continued)
CHECK YOUR PROGRESS
1. Describe how viruses and prions can alter cell functions.
2. Compare and contrast similarities and differences in the replication of a herpes
simplex virus with a human immunodeficiency virus.
3. Draw a diagram of a virus and label the parts.
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4. Sequence the steps in the process of how prions might be transmitted from cattle
to humans.
5. Propose ideas for the development of drugs that could stop viral replication cycles.
6. Write a paragraph explaining why it is difficult to make drugs or vaccines that
effectively fight against HIV, given the fact that each time reverse transcriptase
works, it makes a slight miscopy.
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