AP Biology / Unit 4: Cell Communication and Cell Cycle
4.1 Cell Communication
Notes
Cells signal by:
- Direct contact (gap junctions, plasmodesmata, cell-surface recognition).
- Local signaling (paracrine; synaptic at neurons).
- Long-distance signaling (hormones through the blood, endocrine).
- Bacteria use quorum sensing to sense population density.
Practice
Insulin traveling in the blood to target cells is:
Hormones travel far.
Plasmodesmata let plant cells:
Direct connection.
Quorum sensing lets bacteria:
Signals build up as numbers grow.
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