Which of the following could not elicit a signal...

Which of the following could not elicit a signal transduction response?
a. a protein kinase
b. a virus mimicking a normal signal molecule
c. a peptide hormone
d. a steroid hormone
e. a neurotransmitter

Key Concepts

Signal Transduction

Signal transduction is the process by which cells convert an external signal into a functional response. This generally begins when a signaling molecule (ligand) binds to a specific cell surface or intracellular receptor, leading to a cascade of molecular events that ultimately alter cellular activity.

Ligand-Receptor Interactions

Ligand-receptor interactions are fundamental to initiating signal transduction. The binding of a ligand, such as a hormone or neurotransmitter, to its receptor triggers conformational changes and downstream signaling pathways that regulate various cellular functions.

Protein Kinases

Protein kinases are enzymes that modify other proteins by phosphorylating them, thereby playing a crucial role in propagating and amplifying signals within cells. However, they are components of the signal transduction cascade rather than extracellular ligands that initiate the response.

Peptide Hormones

Peptide hormones are short chains of amino acids that act as signaling molecules. They bind specifically to receptors on the surface of cells, triggering signaling cascades that can result in rapid cellular responses.

Steroid Hormones

Steroid hormones are lipophilic molecules derived from cholesterol. Unlike peptide hormones, they often pass through the cell membrane to bind intracellular receptors, resulting in changes in gene expression and longer-term cellular responses.

Neurotransmitters

Neurotransmitters are chemical messengers used by the nervous system to transmit messages across synapses. Their binding to receptors on target cells initiates signal transduction cascades, essential for rapid communication and processing within the body.

Molecular Mimicry

Molecular mimicry involves the structural imitation of natural ligands by other molecules, such as certain viral proteins. This imitation can enable these molecules to bind to host receptors, potentially triggering or modulating signal transduction pathways in a manner similar to the natural ligand.

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