ch13
The______ of the phage is adsorbed to the host cell.
tail
Another term for a lysogenic phage is______ phage.
temperature
Oncogenic viruses are those that_____ cells into tumor cells
transform
An oncogene might become active when placed on the chromosome in a position where normal controls are not active; this is termed_____
translocation
The abbreviation TSTA stands for tumor-specific_______ antigens.
transplantation
When cells multiply in an uncontrolled way, the excess tissue is called a______
tumor
The virus, once inside the host cell, separates the viral nucleic acid from the capsid; this is called_____
uncoating
During 1993, several deaths caused by a virus occurred in the southwestern United States. Eventually, other cases surfaced in other parts of the country. What method was used to isolate the viral agent? What genus of virus caused the outbreak?
A method referred to as PCR was used to amplify RNA from autopsy specimens and eventually helped researchers to identify Hantavirus as the cause of the mysterious deaths.
The hepadnavirus has genetic material called _NA.
D
Picornaviruses have genetic material called _NA.
R
By what mechanism may retroviruses induce tumors?
Retroviruses induce tumors because some of them contain promoters that turn on oncogenes; others actually contain oncogenes. Also, the fact that the double-stranded DNA of these viruses (produced by reverse transcription of the viral RNA) is incorporated into the DNA of the host and introduces new material to the host's genome can in itself cause problems.
Compare and contrast the lytic and lysogenic cycles of the T-even bacteriophages
The final stage of the lytic cycle involves release of the virions from the host cell. This is accomplished when lysozyme is synthesized within the cell. This enzyme breaks down the cell wall, resulting in lysis and release of the virions. In the lysogenic cycle the phage remains latent, incorporating its nucleic acid into that of the host. The lytic cycle may be induced by some spontaneous event such as exposure to UV light. Lysogeny also results in the following: a. Lysogenic cells are immune to reinfection by the same phage. b. The infected host cell may have new properties. c. Lysogeny makes specialized transduction possible.
What feature of the viral life cycle makes it difficult to produce antiviral drugs?
The problem results from the fact that viruses take over the reproductive machinery of host cells to replicate. This means that drugs that inhibit viral replication will also affect reproduction of the host's cells.
How are viruses able to avoid the action of antibodies?
When viruses infect a host, the host's immune system reacts by producing specific antibodies that act against that virus. Some viruses are able to escape antibodies because proteins on their surface or on their spikes mutate. This means that the antibodies that were originally formed will no longer react with the virus, making them ineffective.
1. Varicella virus. 2. Herpes simplex 2. 3. Epstein-Barr virus. 4. Cytomegalovirus. 5. Cause of Kaposi's sarcoma.
a. Human herpesvirus 3 e. Human herpesvirus 2 b. Human herpesvirus 4 c. Human herpesvirus 5 d. Human herpesvirus 8
1. Cancer of connective tissue. 2. The clumping of red blood cells due to adherence to spikes on viruses. 3. Equivalent to mRNA in a single-stranded RNA virus. 4. RNA to DNA.
a. Sarcoma e. Hemagglutination b. + or sense strand c. Reverse transcription
1. A complete, assembled virus. 2. The subunits making up the protein outer coating of most viruses. 3. The protein outer coating of most viruses. 4. A term derived from the word for poison. 5. A combination of lipids, proteins, and carbohydrates covering the protein coating of a virus. 6. Infectious prion.
a. Virion c. Capsomere b. Capsid e. Virus d. Envelope g. PrPSc
Tumors are malignant when cancerous and____ when not cancerous
benign
1. Describes a method by which an enveloped virus leaves the host cell while acquiring the envelope. 2. Describes growth characteristics of normal cell cultures in glass or plastic containers. 3. A term meaning cancer-causing. 4. Observable changes in a virus-infected cell. 5. The time during which the capsids and DNA of a phage, already formed, are now assembled into complete viruses.
c. Budding g. Monolayer d. Oncogenic e. Cytopathic effect b. Maturation period
Transformed cells lose______ ; that is, they do not stop reproduction when in contact with neighbor cells.
contact inhibition
For several minutes following infection by a phage, no complete phages can be found in the host cell; this is called the_____ period.
eclipse
Many viruses can be grown in_____ eggs.
embryonated
1. Describes the morphology of the capsid of many viruses. 2. A method by which a virus enters an animal host cell. 3. A cell line derived from tissue that normally reproduces for relatively few generations. 4. The HeLa cell line would be placed in this group. 5. A clearing in a "lawn" of susceptible bacterial cells. 6. The number of bacteriophages produced by one bacterial host cell. 7. Presumed agent causing diseases such as sheep scrapie. 8. A bacterial virus. 9. A short strand of RNA virus without a capsid. 10. PrP.
g. Icosahedral h. Endocytosis c. Primary cell line d. Continuous cell line e. Plaque a. Burst size l. Prion i. Phage j. Viroid l. Prion
The term _____refers to the spectrum of host cells the virus can infect.
host range
The herpes simplex virus remains ______in nerve cells of the host for long periods without causing disease.
latent
_______are not solid tumors but an excessive production of white blood cells
leukemias
When the phage DNA is incorporated into the host's DNA, this state is called______
lysogeny
The phage forms a hole in the cell wall using phage____ and drives the tail core through the cell wall.
lysozome
Counts of phage are made in terms of _____units.
plaque-forming
Sometimes the lytic cycle does not occur upon phage infection of a host bacterium. The phage DNA becomes incorporated as a_____ into the host's DNA.
prophage
The type of virus implicated as a cause of AIDS is a____
retrovirus