Stimulated B Lymphocytes Switch from the Synthesis of Membrane-Bound to Secreted

question 12

Multiple Choice

Stimulated B lymphocytes switch from the synthesis of membrane-bound to secreted antibody molecules by increasing the concentration of a subunit of the trimeric CstF complex that cleaves and polyadenylates mRNAs. How does this up-regulation of CstF bring about the production of soluble antibodies?

• A) It favors a strong polyadenylation site in the immunoglobulin primary transcript, creating a longer antibody molecule that is secreted.
• B) It activates a weak polyadenylation site in the immunoglobulin primary transcript and prevents splicing, creating a shorter molecule that is secreted.
• C) It favors a strong polyadenylation site in the immunoglobulin primary transcript, creating a shorter antibody molecule that is secreted.
• D) It activates a weak polyadenylation site in the immunoglobulin primary transcript, creating a longer antibody molecule that is secreted.
• E) It favors a strong polyadenylation site in the immunoglobulin primary transcript, aborting translation and creating a shorter antibody molecule that is secreted.

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Definitions:

Mutation

A change in the DNA sequence within an organism's gene or chromosome, leading to variations in trait expression and possibly to different phenotypes.

Habitat Isolation

A type of prezygotic barrier where two species that could interbreed do not, because they inhabit different habitats and rarely encounter each other.

Environmental Isolation

The separation of population groups by physical barriers or distances, leading to genetic divergence and potentially speciation.

Biological Isolation

The separation of populations of the same species or different species that prevents genetic exchange, often leading to speciation.