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In a signaling cascade, events are described relative to a certain point in the pathway. What are the events that occur after that point called?
AUpstream events
BTerminal ligands
CPrimary messengers
DDownstream events
Answer & Solution
Correct answer: D. Downstream events
1. A signaling pathway is a chain of events triggered after a ligand binds its receptor.
2. Events that occur before a certain reference point in the cascade are called upstream events.
3. Events that occur after that same reference point are called downstream events.
4. Terminal ligands and primary messengers are not the terms used for this timing distinction.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 9 "Cell Communication", section 9.2 | Propagation of the Signal_
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