Question

which of the following statements is true?

a) Metabotropic receptors allow the passage of ions through an opened channel

b) Metabotropic receptors frequently initiate signal transduction cascades

c) Plasma membranes are impermeable to ligands for nuclear receptors, but permeable to ligands that bind receptors in the plasma membrane

e) Plasma membrane receptors usually behave like transcription factors when bound by their ligand

Answer 1

Metabotropic receptors are indirectly linked with ion channels on the plasma membrane of the cell through signal transduction mechanisms.

b) The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a signaling cascade, which is a chain of biochemical events along a signaling pathway. In multicellular organisms, signal transduction pathways have evolved to regulate cell communication in a wide variety of ways.

c) Nuclear Receptors. Nuclear receptors are ligand activated transcription factors that bind non polar regulatory molecules. Because ligands are non polar, they can just diffuse across the plasma membrane to bind to the nuclear receptor that is an intra cellular receptor.

d) Cell-surface receptors, also known as trans membrane receptors, are proteins that are found attached to the cell membrane. These receptors bind to external ligand molecules (ligands that do not travel across the cell membrane).