Types of Cell Signaling
This type of signaling affects only nearby cells.
Local signaling
The “lock” in the lock-and-key model of cell signaling.
The receptor
Small molecules like cAMP or calcium that quickly spread the signal inside the cell.
Second messengers
The stage where the cell does something in reaction to a signal, like turning on a gene.
Response
What is feedback regulation in signaling?
Positive feedback enhances a signal’s effect, while negative feedback reduces it to maintain balance.
Signaling that uses hormones traveling through the bloodstream to reach distant cells.
Long-distance (endocrine) signaling?
This receptor spans the membrane and activates internal proteins when a ligand binds.
Receptor tyrosine kinase (RTK)
This type of protein adds phosphate groups to other proteins to transmit a signal.
A kinase
Controlled cell death that helps with development and tissue health.
Apoptosis
Proteins called phosphatases remove these to help stop a signal.
Phosphate groups
The chemical messenger released at synapses to stimulate neurons.
Neurotransmitter
These receptors are found inside the cell and bind to signals that can cross the membrane, like steroid hormones.
Intracellular receptors
A series of proteins activating each other in sequence to amplify a signal is called this.
Signal transduction cascade
What are the three main stages of cell signaling?
Reception (signal binds to receptor), transduction (signal is relayed and amplified through proteins or second messengers), and response (the cell carries out a specific action).
A cell biologist describes a process in which a protein suddenly “turns on” after receiving a small chemical tag containing phosphorus. This tag changes the protein’s shape, allowing it to interact with new molecules. What process is being described?
Phosphorylation
A researcher finds that a small, nonpolar signaling molecule easily passes through the plasma membrane and binds to a receptor inside the nucleus, altering gene transcription.
What type of signaling molecule is this most likely?
A steroid hormone (intracellular receptor)
Receptors that open or close a channel in the membrane in response to a signal, allowing ions to pass through
Ion channel receptors
The molecule that binds into receptors to set off different signaling responses can ALSO be referred to as a substrate. T or F
FALSE; Substrates are specific to enzymes
Turning on or off genes in response to a signal leads to this kind of cellular response.
Transcriptional response
Failure to terminate growth signals properly can lead to this uncontrolled process.
Excessive cell division
A mutation prevents a cell from removing phosphate groups from proteins after a signal has passed. Which enzymes are likely malfunctioning, and what is the consequence?
Protein phosphatases; signals remain active too long, disrupting cell regulation.
A receptor that activates a G protein when a signal binds, which then triggers downstream effects.
G protein-coupled receptor (GPCR)
The process where small molecules rapidly amplify a signal within the cell, allowing a tiny initial signal to create a large response.
Signal amplification
A researcher identifies a large, polar signaling molecule that cannot cross the plasma membrane. When this molecule is added to a culture of animal cells, it quickly triggers the production of cyclic AMP (cAMP) inside the cells and activates protein kinase A (PKA). What type of receptor does this mystery substance most likely bind to, and why?
The mystery substance most likely binds to a G protein-coupled receptor (GPCR) on the cell surface, because it cannot enter the cell and must use a receptor that activates a second messenger pathway (like cAMP) to relay the signal internally.
A failure in cell signaling pathways is often linked to this type of disease, which involves abnormal cell growth.
Cancer