Receptors for signal molecules __________.

• A. all act via protein kinases
• B. are never found in the nucleus of a cell
• C. all work by opening ion channels
• D. are only found associated with the plasma membrane
• E. may be found embedded in the plasma membrane or found within the cytoplasm or nucleus

Answer: (E)

Verified step by step guidance

1. Understand that receptors for signal molecules are proteins that bind to signaling molecules (ligands) and initiate a cellular response.
2. Recognize that receptors can be located in different parts of the cell, depending on the type of signal molecule they bind to.
3. Identify that some receptors are embedded in the plasma membrane, which allows them to interact with extracellular signal molecules that cannot cross the cell membrane.
4. Acknowledge that other receptors are located within the cytoplasm or nucleus, which typically bind to signal molecules that can diffuse across the cell membrane, such as steroid hormones.
5. Conclude that receptors for signal molecules are versatile and can be found in various cellular locations, including the plasma membrane, cytoplasm, and nucleus, to accommodate different types of signaling molecules.