C.11 - Cell Communication Flashcards
Plant Cell Wall
Extracellular structure made of cellulose fibres in polysaccharides and proteins that distinguishes plant cells from animal cells.
Protects plant cell; Maintains shape; Prevents excessive uptake of water
Plant Cell Wall Layers
–Primary cell wall (relatively thin and flexible)
–Middle lamella (between primary walls, glues adjacent cells together,)
–Secondary cell wall (in some cells between plasma membrane and primary cell wall, strong and durable, provides protection and support)
Plasmodesmata
Channels between adjacent plant cells that perforate cell walls to allow water and solutes (protein and RNA) to pass between cells
Animal Cell Extracellular Matrix
Animal cells lack cell walls but are covered by elaborate extracellular matrix, a complex assembly of compounds.
Support; Adhesion; Movement; Regulation
Intercellular Junctions
Facilitate neighbouring cell to adhere, interact and communicate through direct physical contact
Plants use Plasmodesmata.
Animals use Tight junctions, Desmosomes, Gap junctions
Tight Junctions
neighbouring cell membranes are pressed together to prevent fluid leaking between cells
Desmosomes
Anchoring junctions that fasten cell together and join them
Gap Junctions
For communicating; provides channel between adjacent animal cells
Local Signalling
Direct contact or cell-cell recognition. Local regulator is a messenger molecule that travels short distances.
Long-distance Signalling
Often uses hormones. The ability to respond to a signal depends on whether there is a receptor specific to that signal
processes involved in cell signalling
- Reception: cell detects a signalling molecule that binds to a receptor at the cell surface
- Transduction: reception of signal causes receptor to initiate STP
- Response: the transduced signal triggers a specific response
G-protein-coupled receptors
Works with help of G protein which acts as on/off switch.
Receptor tyrosine kinases
Attaches phosphate to tyrosine; can trigger multiple STP at once
Ion Channels (Ligand-Gated)
Acts as a gate when receptor changes shape; when the molecule binds the gate allows specific ions through the channel
Signal Transduction Pathway
Can amplify a signal. Provides opportunity to coordinate and regulate cell response. Phosphorylation; each receptor activates another protein and so on until it activates.
