MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A research team is investigating a novel protein that acts as a receptor for a specific hormone. They discover that when the hormone binds to the receptor, it induces a conformational change that allows a G-protein to bind and become activated. This activated G-protein then initiates a cascade of intracellular events. Which of the following best describes this process?
- ADirect gene activation
- BEnzymatic catalysis
- CSignal transduction
- DPassive diffusion
Show answer & explanationAnswer & explanation
Correct answer: C. Signal transduction
This scenario describes a classic example of signal transduction, where an extracellular signal (hormone binding) is converted into an intracellular response through a series of molecular events.
Why the other options are wrong
- A. Direct gene activation typically involves steroid hormones that directly enter the cell and bind to intracellular receptors.
- B. Enzymatic catalysis refers to the acceleration of biochemical reactions by enzymes, which is a component but not the overarching process described.
- D. Passive diffusion is the movement of substances across a membrane without energy expenditure, not a complex cellular signaling pathway.
Signal Transduction
The process by which a cell converts an extracellular signal into an intracellular response, often involving a series of molecular events.
- Involves receptors binding to ligands.
- Leads to a cascade of intracellular events.
- Allows cells to respond to their environment.
Memory trick: Signals Transmit Responses