1) a: The most common nucleic acid in
bacterial viruses is DNA, b: the most common nucleic acid in plant viruses is
RNA, c: the most common nucleic acid in fungal viruses is double stranded RNA,
and d: the most common nucleic acid in animal viruses is double stranded DNA,
according to table 19.1

2) Retroviruses are single stranded RNA
viruses. These viruses contain reverse transcriptase, an enzyme that transcribes
its existing RNA into DNA, incorporating that DNA into its host cell’s genetic
information. This is the reverse of the genetic replication process of most
viruses, thus the prefix retro, latin
for behind or backwards. The discovery of retroviruses was an important
breakthrough in molecular genetics, as it challenged the universally accepted
“central dogma of molecular biology” (which stated at the time that the
procedure for information transfer always occured from DNA into RNA.)

3) The viral envelope is a thin layer of material
made up of phospholipids and proteins. It serves to help attach the virus to a
host cell. This membrane that surrounds the nucleocapsid contain remnants of
the host cell’s membrane. Viral envelopes are most commonly found in viruses
that infect animal cells.

4) Virus vaccines are “dead” or inactive
versions of a virus that are injected into an organism to stimulate the immune
system so that it may produce antibodies for that virus. Vaccines help the body
recognize the foreign object as a harmful invader so that specific cells can be
made to destroy the “live” version of the threat in the future.

5) The lytic pathway involves destruction
of the host cell, as the viral DNA replaces the host DNA. The lysogenic pathway
involves integrating viral DNA into the host DNA. In this pathway, all daughter
cells of the host contain viral DNA, allowing virulent information to be spread
more rapidly.

6) A prophage is the genetic instruction from
a bacteriophage that is inserted into a bacterium. A provirus is the term for a
virus genome that is incorporated into a host genome, and it usually refers to
eukaryotic or animal cell genomes.

7) “Pathogens” is the broadest category
that includes all micro agents that can cause disease. There are many types of
pathogens, including viruses. The subcategory of viruses are nonliving
fragments of information that can spread rapidly (infectious) and cause a wide
variety of illnesses and conditions in large organisms.

8) Antibiotics kill bacteria. Since
bacteria are unicellular microorganisms that can evolve and replicate without a
host (among other things), they are considered living. Viruses are nonliving
agents that contain genetic information that is usually harmful to cells. Only
antiviral medication and treatments can destroy viruses, as antibiotics can
only kill microbes that are “alive”.