Chapter 6/ An introduction to viruses, viroids , and prions Flashcards
The microbiologist responsible for the identification of TB, cholera, and anthrax was ________
Robert Koch
The collection of viruses in the human body is called the
virome
______ ______ ______cannot multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses
Obligate intracellular parasites
Are the considered the smallest infectious agents, and can only be seen using an electron microscope.
virus
Spectrum of cells a virus can infect is called
host range
What are the general phases in animal virus multiplication cycle?
* there are 6 parts*
1)Absorption
2)Penetration
3)unceasing
4)synthesis
5)assembly
6)release
What are the two different ways viruses can enter their host?
by fusion or endocytosis
_____ viruses generally are replicated and assembled in the
nucleus
RNA or DNA
DNA
______ viruses generally are replicated and assembled in the
cytoplasm
RNA or DNA
RNA
Viruses can leave the host cell in which two ways?
Budding or (exocytosis) and lysis
cell damage altering microscopic
appearance are referred to as____ _____
Cytopathic effects
what are the two structural capsid types?
Helical and Icosahedral
A capsid type that is three-dimensional , symmetrical polygon,
with 20 sides and 12 evenly spaced corners
Icosahedral
What atypical virus lacks a typical capsid and are covered by a
dense layer of lipoproteins and coarse fibrils
poxviruses
Mammalian viruses capable of initiating tumors are called
oncoviruses
capsid consisting of capsomers forming a
cylindrical nucleocapsid
Helical
Characteristics (5) for placement in a virus family include:
-type of capsid
-nucleic acid strand number
-presence and type of envelope
-overall viral size
-area of the host cell in which the virus multiplies
A pre-formed enzyme that synthesizes DNA or RNA
Polymerases
per- formed enzyme that synthesizes DNA from RNA
Reverse transcriptase
A pre-formed enzyme that copies RNA
Replicases
Some ________ have a polyhedral nucleocapsid
along with a helical tail and attachment fibers
bacteriophages
Release of bacteriophage is a result of cell lysis induced by viral enzymes
and accumulation of viruses. This is known as the ___ cycle
- lytic cycle
either DNA or RNA but never both would be considered a
Viral genome
What are the 6 stages of phage replication?
Absorption
Penetration
Replication
Assembly
Maturation
Lysis & release
Some phages do not complete the lytic cycle . This is when the viral genome inserts into bacterial genome and becomes
an inactive ___
prophage
Prophage is retained and copied during normal cell division
resulting in the transfer of temperate phage genome to all
host cell progeny. This is known as
lysogeny
____ Result in the spread of the virus without killing the host cell
lysogen
Which of the following is a step found in animal virus
multiplication but not in bacteriophage replication?
A. Adsorption
B. Penetration
C. Uncoating
D. Assembly
E. Release
C. Uncoating
Cell (tissue) cultures support viral
replication and permit observation of cytopathic effects. This would be considered…
In vitro OR
In vivo
In vitro
Bird embryos and live animal inoculation are considered
In vitro OR
in vivo
in vivo
misfolded proteins that contain no nucleic acid
Prions
Extremely resistant to usual sterilization techniques
and Cause transmissible spongiform encephalopathies – fatal
neurodegenerative diseases
Prions
Viruses that are dependent on other viruses for replication
Satellite viruses
short pieces of RNA with no protein coat.
-only been
identified in plants
Viroids
Exposure to Nucleases that degrade DNA and RNA would
damage all of the following EXCEPT
A. Animal Viruses
B. Bacteriophage
C. Prions
D. Satellite Viruses
E. Viroids
C. Prions
