Concept 11.1 External signals are converted into responses within the cell
Evolution of Cell Signaling
Local and Long-Distance Signaling
- Cells in a multicellular organism communicate through chemical messengers targeted for cells that may or may not be adjacent
- Cells may communicate directly
- plant cells can connect cytoplasm’s of adjacent cells
- animal cells can communicate directly between membrane-bound cell surface molecules
- Important for embryonic development and immune response
- Cell junctions- Both animals and plants have these, allow molecules to pass readily between adjacent cells w/o crossing plasma membranes.
- Cell-cell recognition- Two cells in an animal may communicate by interaction between molecules protruding from their surfaces.
- Sometimes messenger cells are secreted by signaling cell.
- Some travel short distances, local regulators influence cells in vicinity
The Three Stages of Cell Signaling
Concept 11.2 Reception: A signal molecule binds to a receptor protein, causing it to change shape
Receptors in the Plasma Membrane
Concept 11.3 Transduction: Cascades of molecular interactions relay signals from receptors to target molecules in the cell
Signal Transduction Pathways
Protein Phosphorylation and Dephosphorylation
Small Molecules and Ions as Second Messengers
Concept 11.4 Response: Cell signaling leads to regulation of cytoplasmic activities or transcription
Cytoplasmic and Nuclear Responses
Fine-Tuning of the Response