Types of Cell Signaling
This type of signaling occurs when the cell communicates with itself via secreted signals.
autocrine signaling
The first step when a ligand binds to a receptor is called this
reception
This type of feedback loop reduces a deviation from a set point to maintain homeostasis
negative feedback
The cell cycle stage in which DNA is replicated is called this
S phase (Synthesis phase)
If a receptor on the cell surface cannot bind its ligand, the signal fails at this stage.
reception
A hormone released in the bloodstream to distant cells is using this type of signaling.
endocrine signaling
After reception, the signal is passed along in a cascade — this process is called what?
transduction
This type of feedback amplifies a process
positive feedback
During mitosis, the chromosomes line up at the middle of the cell during this stage
metaphase
A kinase cascade amplifies the signal by adding these chemical groups to proteins
phosphate groups (phosphorylation)
Signaling in which cells are connected by gap junctions or direct contact: this term.
juxtacrine (or direct contact) signaling
The final effect of a signal cascade (e.g., gene expression or enzyme activation) is called this.
response
If a checkpoint protein fails and the cell divides uncontrollably, this disease can result.
cancer
The phase when sister chromatids separate and move toward opposite poles is called this
anaphase
If a cell’s checkpoint fails and DNA with errors is passed on, this will most likely happen.
mutation or tumor formation or cancer
Local signaling to nearby cells (not self, not distant) is called this
paracrine signaling
Name one second messenger commonly used in signal transduction
cyclic-AMP (cAMP) or calcium ions (Ca²⁺)
This checkpoint occurs after DNA replication, before mitosis begins
G₂ checkpoint
Cells that are not actively dividing can exit the cycle into this stage
G₀ phase (G zero)
A hormone binds an intracellular receptor and changes gene expression — this is an example of what kind of signaling receptor?
intracellular (nuclear) receptor
In plants, plasmodesmata allow molecules to pass directly between cells. This is an example of which type of signaling?
direct contact (juxtacrine) signaling
In a phosphorylation cascade, how does each kinase activate the next step in the pathway?
adding a phosphate group (phosphorylation)
During the G₁ checkpoint, a cell will enter the G₀ phase if it doesn’t receive this crucial internal or external signal.
growth factor or cyclin/CDK signal
Describe the difference between cytokinesis in plant and animal cells.
In animals, the cell membrane pinches inward (cleavage furrow); in plants, a cell plate forms to separate the new cells.
Explain how signal amplification benefits the cell during transduction.
A single ligand can trigger the activation of many molecules and a large cellular response, saving energy and speeding up the process.