A.P. BIOLOGY:
Chapter 11: Cell Communication
Key Concepts:
1. External Signals are converted into responses with the cell
-A signal transduction pathway is a series of steps in which a signal on a cell’s
surface is converted into a specific cellular response.
-Cells can communicate directly by cell-to-cell contact (Gap Junctions and
Plasmodesmata)
-Cells can also communicate by the use of messenger molecules which can travel both
long (hormones, nerve cells) and short (local regulators, growth factors) distances.
There are Three Steps of Cellular Communication (See Figure 11.5, page 204):
2. Reception: A signal molecule binds to a receptor protein, causing it to change shape
-Reception is the target cell’s detection of a signal molecule coming from outside the cell.
A chemical signal is detected when it binds to a receptor protein located at the
cell’s surface or inside the cell.
3. Transduction: Cascades of molecular interactions relay signals from receptors to
target molecules in the cell
-The transduction stage converts the signal that was received to a form that can bring
about a specific cellular response. It most often requires a sequence of changes in
a series of different molecules.
4. Response: Cell signaling leads to regulation of cytoplasmic activities or
transcription.
-The transduced signal finally triggers a specific cellular response. The response may be
almost any cellular activity, such as catalysis by an enzyme, rearrangement of the
cytoskeleton, or activation of genes in the nucleus.