Name ______________________________________ ___________________________date _________ hour _______
Chapter 18.1 Viruses: Guided Reading Activity
1.
Turn to page 489. Read the opening paragraph (next to the picture)
a. What are some examples of childhood diseases? Did you have any of these?
2.
Why is getting one of these diseases rare now?
3.
Examine the objectives and vocabulary to the right of the picture. You will be learning about theses items and will have to
know them. Consider making note cards or a vocabulary list.
4. Read what is a Virus?
a. Define VIRUS–
b. Why do most biologists consider viruses to be non-living?
c. They don’t carry out ___________________, ____________, or ______________.
They can ____________________________ (make copies of themselves)
d. Define HOST CELL –
e. How are viruses named?
f.
Continue onto page 490. Some viruses are given code numbers for viruses that infect the same _______________.
What is an example of this naming system?
g. Define BACTERIOPHAGE –
5. Examine the minilab 18-1. The reference line in the picture is 0.5 micrometers; the limit for viewing objects under a light
microscope is 0.2 micrometers. Knowing this information, do you think that a virus can be seen with a light microscope?
Explain___________________________________________________________________________________
__________________________________________________________________________________________
What important invention allows us to view viruses (think about this)? ______________________________
6. Read Viral Structure. (viral structure is one of the key objectives)
a. Inner core
(describe)___________________________________________________________________________
___________________________________________________________________________________
b. CAPSID(describe)____________________________________________________________________
___________________________________________________________________________________
c. Additional Outer layer
(describe)_________________________________________________________________________
_________________________________________________________________________________
d. Turn to page 167 – read the last paragraph. What does RNA do?
e. Now, turn back to page 490 and continue with the second paragraph of Virus Structure.
Viral nucleic acid is either _______________ or ______________.
It contains instructions for ______________________________________________________
f.
What determine the viruses shape?
g. There are ________ shapes.
h. What does the protein arrangement (viral shape) play an important role in?
i.
Examine figure 18.1 on page 491. Describe the 4 viral shapes and draw a sketch, and label of each in the
boxes below. Your drawings need only be the basic shapes
7. Read Attachment to host cell (page 490)
a. In order to replicate a virus must first ___________________________________________.
b. Where does it attach itself? _________________________________________________
c. What analogy is used to describe the attachment process and why?
8. Turn to page 492. Read Attachment is a specific process.
a. Why can a virus only attach to a few specific cells?
b. Describe how this works in the T4 virus.
c. Why was the eradication (gone completely) of the smallpox virus possible?
9. Read Viral Replication Cycles (this is also one of the main objectives)
a. Once attached to the plasma membrane of the _____________________, the virus ___________the cell
and takes over its ________________________.
b. What are the two ways that virus can get into a host cell?
1. ___________________________________________________________________________________
___________________________________________________________________________________
____________________________________________________________________________
2.
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________
10. Lytic Cycle (page 493) ( LYTIC CYCLE is one of your vocabulary words)
a. A short description can be found next to the picture sequence on page 492 (figure 18.2). How does
virus make new viruses in this process?
b. Now, read the section on page 493. Does the host cell survive this process? ___________
c. Think of an analogy that relates this process of the virus taking over the host cell and using the host
cells own materials to make copies of itself.
11. Read Lysogenic cycle (LYSOGENIC CYCLE is one of your vocabulary words)
a. Define LYSOGENIC CYCLE –
b. Does the host cell survive this process? ____________c. How is the lysogenic cycle similar to the lytic cycle?
d. How do they differ?
e. Define PROVIRUS – (include whether it affects the host cells functioning)
f.
g.
Every time the host cell reproduces (mitosis) the provirus is _____________________.
What may happen at any time?
h. Examine the Problem Solving Lab 18-1 on page 494. Complete the questions.
1.
lytic_________________________________________________________________________________
lysogenic_____________________________________________________________________________
2.
________________________________________________________________________________________
________________________________________________________________________________________
3.
________________________________________________________________________________________
_______________________________________________________________________________________
4.
________________________________________________________________________________________
________________________________________________________________________________________
12. Read Disease symptoms of proviruses on page 494
a. Describe how the lysogenic process explains the reoccurrence of cold sores.
b. What may cause a provirus to be activated?
c. What may happen to you later in life if you have had the chicken pox?
13. Thinking Question. What are the main differences between the lytic cycle and the lysogenic cycle?
14. Read Release of viruses starting on page 494.
a. What two ways release viruses from the host cell?
1.______________________________________________________________________
2. _____________________________________________________________________
15. Read retroviruses starting on page 495.
a. Define RETROVIRUS –
b. Once inside the host cell, the _________________ make __________ from __________.
c. The double stranded viral DNA is _____________________ into the
______________________________________ and becomes a ________________.
16. Read HIV: An infection of white blood cells on page 496
a. Why does an infected person not appear sick?
b. Why is this a problem?
c. Eventually HIV leads to ___ ___ ___ ___.
d. Why do people gradually lose white blood cells?
e. Why are AIDS patients very susceptible to other diseases (typically AIDS patients die from pneumonia,
fungal infections, etc)?
17. Read Viruses and Cancer on page 496
a. How can viruses cause cancer?
18. Read Plant Viruses
a. How many plant diseases are caused by viruses? __________
b. Not all plant viruses are fatal. What is the example given in the book of a situation where the virus is
not harmful, but useful for the flower industry?
19. Read Origin of Viruses (page 497)
a. Where might viruses have originated?
b. What is some evidence for this hypothesis?
c. According to this hypothesis, viruses are more closely related to their ____________ then they are to
_______________________.