Exam 2 Study Guide
Microbiology (BIOL 2104)
Questions and Complete
Solutions Graded A+
Denning [Date] [Course title]
, What are the characteristics of viruses? - Answer: they are not cells; are obligate intracellular parasites
of other organisms; do not independently fulfill the characteristics of life; active only inside host cells;
have basic structure of protein shell surrounding nucleic acid; ubiquitous in nature; ultramicroscopic in
size; lack enzymes for basic metabolic processes; can't synthesize proteins on their own; infectious
particles
What are the components of viruses? their functions? - Answer: Consist of a covering (capsid, envelope)
and a central core (DNA/RNA, protein). Coverings protect the virus and surround it. The central core
houses the genetic material. Have spikes, which allow viruses to dock with their host cells
viroid - Answer: an infectious agent that lacks a capsid and consists of a closed circular RNA molecule;
capable of infecting plants
virion - Answer: an elementary virus particle in its complete morphological and infectious form. Consists
of a nucleic acid core surrounded by a capsid
prion - Answer: a mutated protein capable of causing brain deterioration in cattle or other mammals.
Contains no nucleic acid. Examples include BSE and Creutzfeldt-Jakob disease
satellite virus - Answer: a virus which is dependent on another virus for survival
What is an envelope virus and how does it obtains its envelope? - Answer: an envelope virus is a
nucleoprotein that is surrounded by a membrane. It obtains its envelope from being released from a
host cell, in which they then take with them a bit of the host's plasma membrane
How do animal viruses multiply? Sequence of events? - Answer: 1. adsorption: the virus attaches to its
host cell by specific binding of its spikes to cell receptors
2. penetration: the virus is engulfed into a vesicle and its envelope is uncoated
3. uncoating: frees the viral RNA into the cell cytoplasm
4. synthesis: under the control of viral genes. the cell synthesizes the basic components of new viruses
5. assembly: viral spike proteins are inserted into the cell membrane for the viral envelope; nucleocapsid
is formed from RNA and capsomeres
6. release: enveloped viruses bud off the membrane, carrying away an envelope with the spikes
Microbiology (BIOL 2104)
Questions and Complete
Solutions Graded A+
Denning [Date] [Course title]
, What are the characteristics of viruses? - Answer: they are not cells; are obligate intracellular parasites
of other organisms; do not independently fulfill the characteristics of life; active only inside host cells;
have basic structure of protein shell surrounding nucleic acid; ubiquitous in nature; ultramicroscopic in
size; lack enzymes for basic metabolic processes; can't synthesize proteins on their own; infectious
particles
What are the components of viruses? their functions? - Answer: Consist of a covering (capsid, envelope)
and a central core (DNA/RNA, protein). Coverings protect the virus and surround it. The central core
houses the genetic material. Have spikes, which allow viruses to dock with their host cells
viroid - Answer: an infectious agent that lacks a capsid and consists of a closed circular RNA molecule;
capable of infecting plants
virion - Answer: an elementary virus particle in its complete morphological and infectious form. Consists
of a nucleic acid core surrounded by a capsid
prion - Answer: a mutated protein capable of causing brain deterioration in cattle or other mammals.
Contains no nucleic acid. Examples include BSE and Creutzfeldt-Jakob disease
satellite virus - Answer: a virus which is dependent on another virus for survival
What is an envelope virus and how does it obtains its envelope? - Answer: an envelope virus is a
nucleoprotein that is surrounded by a membrane. It obtains its envelope from being released from a
host cell, in which they then take with them a bit of the host's plasma membrane
How do animal viruses multiply? Sequence of events? - Answer: 1. adsorption: the virus attaches to its
host cell by specific binding of its spikes to cell receptors
2. penetration: the virus is engulfed into a vesicle and its envelope is uncoated
3. uncoating: frees the viral RNA into the cell cytoplasm
4. synthesis: under the control of viral genes. the cell synthesizes the basic components of new viruses
5. assembly: viral spike proteins are inserted into the cell membrane for the viral envelope; nucleocapsid
is formed from RNA and capsomeres
6. release: enveloped viruses bud off the membrane, carrying away an envelope with the spikes
