Cell Communication
Why cells must communicate
Coordinating cell activities
This type of signaling requires physical contact between cells.
Direct contact signaling.
The first stage of cell signaling, when a ligand binds to a receptor.
Reception
The growth and reproductive cycle of a eukaryotic cell.
The cell cycle.
A feedback mechanism that counteracts change to maintain stability.
Negative feedback.
This allows unicellular organisms to detect and respond to changes in their environment.
Cell signaling.
This type of signaling acts on nearby target cells.
Paracrine signaling.
The stage of signaling involving a series of intracellular relay steps.
Transduction
The phase of the cell cycle during which DNA is replicated.
S phase
A feedback mechanism that amplifies change to complete a process.
Positive feedback.
This determines whether a cell will respond to a signaling molecule.
The presence of a specific receptor.
This type of signaling uses neurotransmitters across synapses.
Synaptic signaling.
The final stage of cell signaling that produces a cellular action.
Response
A possible result when checkpoints fail and apoptosis does not occur.
Uncontrolled cell division (cancer).
Sweating to cool the body is an example of this type of feedback.
Negative feedback.
This bacterial communication method depends on population density.
Quorum sensing.
This type of signaling involves hormones traveling through the bloodstream.
Endocrine signaling.
A second messenger produced from ATP in the epinephrine pathway.
cAMP
Control points that ensure critical events are completed before cell cycle progression.
Checkpoints
Oxytocin release during childbirth is an example of this type of feedback.
Positive feedback.
This coordinated behavior can result from quorum sensing in bacteria.
Biofilm formation or toxin production.
A cell releases a chemical that affects only nearby cells in the same tissue.
Paracrine signaling
Enzymes that add phosphate groups to proteins.
Protein kinases.
Protein complexes that regulate progression through the cell cycle.
Cyclin-Cdk complexes.
The primary reason negative feedback is essential in living systems.
Maintenance of homeostasis.