Recombination Signal Sequences Are Conserved Heptamer and Nonamer Sequences That $\kappa$

question 33

Multiple Choice

Recombination signal sequences are conserved heptamer and nonamer sequences that flank the V, J, and D gene segments which undergo recombination to generate the final V region coding exon. Some of these have 12-nucleotide spacers between the heptamer and nonamer, and others have 23-nucleotide spacers. The reason recombination signal sequences come in these two forms is:

• A) To ensure the correct assembly of gene segments so that a V_H recombines to a D_H and not to another V_H, for instance
• B) To ensure that the heptamer and nonamer are found on the same face of the DNA double helix
• C) To ensure that \(\kappa\) , \(\lambda\), and heavy chains recombine within a locus and not between loci
• D) To ensure that \(\kappa\) , \(\lambda\), and heavy chain gene segments do not undergo recombination with non-immunoglobulin genes
• E) To ensure that the RAG recombinase cuts the DNA between the last nucleotide of the heptamer and the coding sequence

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Definitions:

Weber Fraction

A principle stating that the just noticeable difference between two stimuli is proportional to the magnitude of the stimuli, a fundamental concept in psychophysics.

Stimulus

Anything in the environment that can trigger a physical or behavioral change in an organism.

Nativism

The theory that certain skills or abilities are "native" or hard-wired into the brain at birth.

Empiricism

A philosophical stance positing that knowledge comes primarily from sensory experience.