pathways of communication
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Pathways of Communication. TED Video: Bacteria Communicate?. TED Video. Cell to Cell Interactions. Explain the following statement: The sum is greater than the parts. Who speaks?. Cells in constant communication Unicellular OR Multicellular. With other organisms: Cooperation - PowerPoint PPT PresentationTRANSCRIPT
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Pathways of Communication
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TED Video: Bacteria Communicate?
TED Video
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Cell to Cell Interactions
Explain the following statement:
The sum is greater than the parts.
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Who speaks?•Cells in constant communication
Unicellular OR Multicellular
With other organisms:• Cooperation• Competition
With other cells:• Cooperation• Successful
survival
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Making the connections..•Cells excrete layer surround membrane
•The ECM! (extracellular matrix)▫Aids in:
Structure Protection
Filaments resist TENSION
Ground material resists COMPRESSION
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ECM in plants•Primary Cell Wall – initial fiber
composite (cellulose microfibrils filled with pectin)
•Secondary Cell Wall – secreted by some plants▫Between membrane & 1º cell wall▫[High] of lignin (sturdy)
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• Layer of pectins between cell walls(or membranes)
• “glues” cells• Degradation = Cell
separation
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ECM in animals•Proteins NOT polysaccharides•Collagen = pliability•Amt varies
▫# surrounding cells▫Cell function (Ex: elastin in lungs)
•Structural properties: integral proteins bind to ECM proteins▫adjacent cells can bind at common
connections in ECM = increased stability
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Predict! What would happen if ECM-cell
connection was lost? Can you think of an example?
•Cells migrate•Ex: malignant cancer
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Reinforcement team in the Middle Lamella2 types of reinforcers:1. Tight Junctions – “quilting” formed by
connecting proteins in adjacent cells▫ Create water tight seal▫ Separate solutions (ie. Stomach
fluid/blood)▫ Dynamic
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Tight Junctions
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2. Desmosomes – connections between cytoskeletons of adjacent cells; “bolt” cells
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**Cells Selectively Adhere**
•Proteins involved in cell binding – cadherins
cell specificity
Like cells aggregate
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Cellular connections…
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Mechanisms of Communication
the method behind cell “talking” near & far
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Close communication in PLANTS!!!•Plasmodesmata – gaps in cell wall,
continuous cell membrane & plasma▫Smooth ER runs through
▫Regulated by proteins
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How are these different from plasmodesmata?
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•gap junctions – holes in ECM and membrane specialized proteins admit:
H2O aa’s sugar nucleotide
Close communication in ANIMALS!!!
Coordinate reactions (Ex: muscle contractions; heartbeats)
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Fig. 11-4Plasma membranes
Gap junctionsbetween animal
cells(a) Cell junctions
Plasmodesmatabetween plant
cells
(b) Cell-cell recognition
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Distant communication: 4 STEPS!1. Receive
2. Process
3. Respond
4. Terminate
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1. RECEIVE•Signals are chemical “language”
(hormones)•Bind/Ligand to receptors (intra- OR
extracellular)
Characteristics:1.Cell specific2.Dynamic – overstimulation =
adaptation3.Potential blockage
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•Upon receipt, response initiation begins•2 types:1. Direct
hormone enters
binds to receptor
complex enters nucleus
binds to DNA
directs gene expression
1. PROCESS
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2. Indirecthormone binds to receptor
signal transduction begins
G-proteins
Receptor protein kinases
Both Pathways Result in: 1. Conversion of extracellular signal to intracellular
message2. Amplification of a message many times over
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G-proteins Coupled Receptors
Animations <~ Watch this!
G-protein can activate an
enzyme OR an effector that will go on to
activate
Ions, larger compounds (Ex:
Ca2+, cAMP)
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Ex: Calcium Pathway
Maintaining electrical potential across
membranes, cofactor for many enzymes
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•Phosphorylation cascades amplify signal
•Activated enzymes induce a signal response
Receptor Protein Kinases
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•Activity within cell altered by:▫Second
messengers
▫Phosphorylation cascades
3. Response
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4. Deactivation•Built in systems to
“turn off”▫Hydrolyze GTP/ATP
▫Stop phosphorylation
▫Overstimulation