Microbiology: Principles and Explorations, 9th Edition: Chapter 10 Flashcards
A chemical component that is found in all viruses is:
Which of the following properties do viruses have in common with the bacterial section containing Rickettsiae and Chlamydiae?
(a) They are both the same size
(b) They both have RNA strands for their genomes
(c) They both obligate intracellular parasites
(d) They both contain enzymes for glucose metabolism
(e) None of the above
Viruses that contain latent (usually in neurons) for many years are most likely:
What type of viruses contain the enzyme lysosome to aid in their infection?
(b) Animal viruses
(c) Plant viruses
(d) Fungal viruses
(e) Human viruses
The period of viral growth that occurs from the time of host cell penetration to the time when new virions are first assembled within the host cell is called:
(a) Lag phase
(b) Latent period
(c) Replication phase
(d) Eclipse period
(e) Generation time
Bacteriophages are readily counted by the process of:
(c) Plaque assays
(d) Tissue cell culture
(e) Electron microscopy
A type of cell culture that can reproduce for an extended number of generations and is used to support viral replication is a:
(a) Primary cell culture
(b) Continuous cell line
(c) Cell strain
(d) Diploid fibroblast cell
(e) Connective tissue
Which of the following is not a DNA virus?
All of the following are true about retroviruses EXCEPT:
(a) Retroviruses cause tumors and leukemia in rodents, birds, and humans.
(b) Retroviruses cause acquired immune deficiency syndrome (AIDS) in humans.
(c) Retroviruses cause reverse transcriptase to form a complementary strand of DNA, which is then replicated to form double-stranded DNA (dsDNA).
(d) dsDNA must migrate to the cell host, whereby it becomes a provirus.
(e) Retroviruses have two complete copies of ( - ) sense RNA.
Bacteriophages that can enter into stable, long-term relationships with their hosts are called:
(a) Lytic phages
(b) Defective phages
(c) Virulent phages
(d) Lazy phages
(e) Template phages
Unlike positive ( + ) strand RNA viruses, what must negative ( - ) strand RNA viruses package within virions in order to make mRNA upon infection of a new host cell?
(b) Integrase enzymes
The replication of animal viruses differs from the replication of bacteriophages in what way?
(a) Once in the host cell, animal viruses undergo a process of "uncoating" whereby the viral genome is separated from its protein coat by proteolytic enzymes; the viral genome in a bacteriophage is ready to go once injected into the bacterial host cell.
(b) Compared to the bacteriophage replication, synthesis in animal virus replication can take much longer.
(c) In the penetration stage, bacteriophages produce lysozyme to weaken the bacterial cell wall and inject their DNA through the tail core into the bacterial cell, whereas animal viruses either fuse their envelope with the host's plasma membrane or enter by endocytosis.
(d) The maturation stage in animal enveloped viruses is longer than that of bacteriophage replication.
(e) All of the above are ways in which animal viruses differ from bacteriophage replication.
A virophage is best described as:
(a) A bacteriophage that requires a helper virus
(b) An animal virus that can also infect bacteria
(c) A giant virus
(d) A phage that is used therapeutically to treat bacterial infections
(e) A satellite virus that inhibits its helper virus (i.e., its host virus)
Creutzfeldt-Jakob disease (CJD), kuru, scrapie, and mad cow disease are caused by:
(c) DNA viruses
(e) RNA viruses
The human virus that has been associated with Burkitt's lymphoma (a malignant tumor of the jaw) is:
(b) Human papilloma virus
(d) Epstein-Barr virus
Viruses that can induce defects during embryonic or neonatal development (teratogenesis) in humans are:
(a) Herpes simplex virus types I and II
(e) a, b, and d
Which is NOT true regarding viruses and cancer?
(a) An estimated 15% of human cancers arise from viral infections.
(b) Cancers can be caused by both RNA tumor viruses and DNA tumor viruses.
(c) Oncogenes are made up of DNA.
(d) All neoplasms are malignant.
(e) Examples of human cancers believed to arise from viral infections include Kaposi's sarcoma, adult T-cell leukemia/lymphoma, and cervical cancer.
Key characteristic prions:
(a) Found only in brain cells
(b) Heat-resistant genomic material
(c) Ability to form fibrils
(d) Denatured by urea, a protein disrupting agent
(e) All of the above