1. Cell Communication Ch. 6, 7, and 11

2. Direct Contact Plants plasmodesmata connect cytoplasm

3. Figure 6.31 Interior of cell 0.5  m Plasmodesmata Plasma membranes Cell walls

4. Direct Contact Bacteria quorum sensing coordinate behaviors to produce a biofilm

5. Figure 11.3 Individual rod-shaped cells Spore-forming structure (fruiting body) Aggregation in progress Fruiting bodies 1 2 3 0.5 mm 2.5 mm

6. Direct Contact Animals have nonmotile cilia that function like a receiving antenna Most vertebrate cells have one per cell Crucial for brain function and embryonic development

7. Animal cell junctions Tight junctions-prevent leakage of extracellular fluid (skin cells are watertight) Anchoring junctions (desmosomes)- act like rivets to anchor cell to cell (form strong sheets of cells, bind muscle cells together) Gap junctions- like plasmodesmata in plants; these are communicating junctions necessary for communication especially in heart muscle and embryoes

8. Figure 11.4 Plasma membranes Gap junctions between animal cells Plasmodesmata between plant cells (a) Cell junctions (b) Cell-cell recognition

9. Figure 6.32 Tight junctions prevent fluid from moving across a layer of cells Tight junction TEM 0.5  m TEM 1  m TEM 0.1  m Extracellular matrix Plasma membranes of adjacent cells Space between cells Ions or small molecules Desmosome Intermediate filaments Gap junction

10. Membrane Structure Membrane carbohydrates allow for cell to cell recognition Usually are glycoproteins but may be lipoproteins

11. Local Regulators Influence cells in vicinity In animals growth factors stimulate nearby cells to grow and divide Paracrine signaling- local regulator diffuses through extracellular fluid Synaptic signaling- neurotransmitters

12. Figure 11.5a Local signaling Target cell Secreting cell Secretory vesicle Local regulator diffuses through extracellular fluid. (a) Paracrine signaling (b) Synaptic signaling Electrical signal along nerve cell triggers release of neurotransmitter. Neurotransmitter diffuses across synapse. Target cell is stimulated.

13. Long Distance Signaling Hormones using signal transduction pathways

14. Figure 11.5b Long-distance signaling Endocrine cell Blood vessel Hormone travels in bloodstream. Target cell specifically binds hormone. (c) Endocrine (hormonal) signaling

15. Cell Signaling Leads to regulation of transcription factors or cytoplasmic factors All cell communication relies on specific receptor molecules for binding

16. Figure 11.15 Growth factor Receptor Reception Transduction CYTOPLASM Response Inactive transcription factor Active transcription factor DNA NUCLEUS mRNA Gene Phosphorylation cascade P

17. Apoptosis Programmed cell death is a means of cell communication When this mechanism is activated or deactivated will determine body structures

18. Figure 11.22 Interdigital tissue Cells undergoing apoptosis Space between digits 1 mm