GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Receptors and Channels
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
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Example Questions
Example Question #7 :Cellular Signals And Communication
Toll-like receptors (TLRs) are transmembrane receptors that have an extracellular leucine-rich region and an intracellular toll-interleukin region domain. What is the primary function of TLRs?
Promote cell-cell adhesion
Elicit innate immune responses by recognizing microbial associated molecular patterns
Promote differentiation by recognizing notch ligands
Promote sex-specific organ growth by binding estrogen or testosterone
Bind epidermal growth factor to promote cell proliferation
Elicit innate immune responses by recognizing microbial associated molecular patterns
The correct answer is elicit innate immune responses by recognizing microbial associated molecular patterns. TLRs are pattern recognition transmembrane receptors that recognize bacterial components, such as lipopolysaccharides and flagellin, and viral components such as single stranded DNA. Upon recognition by the leucine rich region, TLRs dimerize to facilitate signal transduction (via the toll-interleukin region domain) to downstream pathways to promote inflammation and recruitment of macrophages.
Example Question #8 :Cellular Signals And Communication
Which of the following is not true concerning G protein-coupled receptors (GPCRs)?
They use GTP as energy when activated.
They are found on the outside of cell membranes.
All GPCRs will increase cAMP levels in the cell.
They can recognize peptide hormones as their ligand.
All GPCRs will increase cAMP levels in the cell.
G protein coupled receptors are by far the largest class of cell surface receptors. They can respond to a large variety of extracellular signaling molecules, and can elicit a great deal of responses inside cells. With such diversity, it should come as no surprise that not all GPCRs will increase cAMP levels in the cell. In fact, many can display an inhibitory role, and decrease cAMP levels by preventing its production.
Example Question #9 :Cellular Signals And Communication
The sodium-potassium pump works by bringing sodium__________cells and potassium__________cells through the use of ATP.
into . . . into
out of . . . into
into . . . out of
out of . . . out of
None of these
out of . . . into
The sodium-potassium pump is a type of active transport that brings sodium out of the cell and potassium into the cell. This is in the opposite direction of their natural gradient. The fact that it is going in the opposite direction requires this pump to need energy, or, ATP.
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