EXERCISES, LESSON 7
INSTRUCTIONS: Answer the following items by completing the statement or by writing
the answer in the space provided.
After you have completed all of these items, turn to "Solutions to Exercises" at the
end of the lesson and check your answers with the solutions.
The structure of a virus consists of a c__e, a c___d, and an e____e. The core
consists mainly of a n___c acid, either DNA or RNA, never both together. The
capsid is a protective protein coat around the c___e. It is constructed of individual
subunits termed c_____s. The envelope is a l__d outer covering; it may or may
not be pr___t depending on the virus.
Viruses are classified by the following properties: m_______gy, structure, and
cytopathic effects in cell c____es.
Acquired immunodeficiency syndrome (AIDS) is caused by the human i________y
virus (HIV). Epidemiological data and serological data suggest that the viral
infection began in Central A____a.
4. Human Immunodeficiency Virus belongs to a unique class of viruses, distinguished by
the presence of an e___e that catalyzes the formation of ____ from RNA. The catalyzing
a reverse t_____e, and viruses that contain it are called r_____s. The HIV
is a cytopathic retrovirus that appears to be genetically related to some of the other
The virus is approximately 110-140 n_meters in size and has an outer envelope
surrounding the core. The core contains __ (the genetic information), reverse
t____e, and p24, which is a p___n. The p24 protein is antigenic, and a____s
against it are detected in the ELISA test and Western blot. The envelope contains
two important glycop____s. Glycoprotein 41 (gp 41) spans the m___e and is also
antigenic. The other protein, gp 120, is the major o___r membrane glycoprotein of
HIV. The envelope gene that codes for a portion of the virus's outer membrane
v__________s considerably from isolate to isolate. An effective vaccine for AIDS
would therefore need to protect against many different s______s of the virus. The HIV
contains a gene, called the TAT (trans-a____or) gene, whose product acts as a
powerful promotor of viral DNA r____tion. This promotion of viral replication at the
expense of c____r replication may be an important mechanism in virally induced