GRE Subject Test: Biochemistry, Cell, and Molecular Biology › Help with Receptors and Channels
The sodium-potassium pump works by bringing sodium __________ cells and potassium __________ cells through the use of ATP.
out of . . . into
into . . . out of
into . . . into
out of . . . out of
None of these
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.
Which of the following is not true concerning G protein-coupled receptors (GPCRs)?
All GPCRs will increase cAMP levels in the cell.
They are found on the outside of cell membranes.
They can recognize peptide hormones as their ligand.
They use GTP as energy when activated.
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.
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?
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
Promote cell-cell adhesion
Bind epidermal growth factor to promote cell proliferation
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.