Point mutations in the hemagglutination (HA) or neuraminidase (NA) genes during viral ribonucleoprotein (RNP) replication give rise to new strains. This mechanism is known as the antigenic:
a. drift.
b. shift.
c. re-assortment.
d. modification.
A
The antigenic drift is caused by sequential point mutations in the HA or NA genes that occur during viral RNP replication and immune selection, which give rise to new strains; thus, the an-tigenic drift gives the virus the ability to re-infect nonimmune susceptible hosts each season. Another phenomenon is the antigenic shift. Influenza A solely possesses this mechanism; it in-volves the complete re-assortment of the segmented viral genome during a co-infection with a nonhuman animal, which results in major antigenic change and periodic worldwide outbreaks (pandemics) of a never-before-circulated type of influenza A virus. Influenza B undergoes anti-genic change very slowly.
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Sequence assembly is accomplished by:
A. aligning the fragments in the laboratory by running them through gel electrophoresis. B. aligning the fragments on paper. C. aligning the fragments by using a complex computer program. D. aligning the fragments by joining histones. E. None of the answer options is correct.
The condition in the host that results from pathogenic parasitic organism growing and multiplying within or on the host is called
A. an infection. B. pathogenesis. C. an infectious disease. D. All of the choices are correct.
Flat bones
What will be an ideal response?
An essential amino acid is one that must be provided in the diet
____________________ Indicate whether the statement is true or false.