Post on 31-Dec-2015
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CELL -CELL INTERACTIONSCH 11
Explain why this is the result of cell to cell communication
What characteristics are noted about cell communication here ?
I. Evolution of Cell Communication
• Bacteria communicate with each other in order to respond to environmental changes
• The mechanism of cell communication is similar in both prokaryotes and eukaryotes:
• o Signal molecule secreted by one cell binds to receptor on target cell
• o Target cell responds • what does this tell us about the evolution of cell
communication?
. II. How cells communicate with each other
A. Local signaling: Direct contact and cell-cell recognition
B. Local signaling using local regulators: paracrine and synaptic signaling
• Signal molecules only travel short distances
C. Long distance signaling: endocrine signaling
• Involves hormones
• What characteristics are fundamentally the same in cell communication across the domains?
• What allows a cell to respond to a signal?
III. The transmission of a signal from one cell to another:
A. The 3 stages of cell signaling: • Reception: • Transduction: • Response:
Identify similarities and differences in these 2 modes of cell communication
B. Reception
• signal molecule binds to receptor causing it to change shape and become activated
• this binding is specific1. cell surface receptors:• hydrophilic signal molecules bind to
receptors that span the cell membrane
2. If it a steroid hormone (lipid soluble): • Steroid diffuses across phospholipid bilayer,
binds to its receptor in the cytoplasm, and travels to nucleus and either increases or decreases expression of certain genes
http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter18/animation__mechanism_of_steroid_hormone_action__quiz_1_.html
C. Signal Transduction :usually involves multiple steps
• Identify the 3 stages of cell signaling in this diagram
• What is happening during transduction?
• Binding of signal activates receptor • the receptor activates another protein,
which activates another, and so on, until the protein producing the response is activated
• Multistep pathways can amplify a signal: A few molecules can produce a large cellular response
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter7/animations.html
D. Response:
• Ultimately, a signal transduction pathway leads to regulation of one or more cellular activities
• The response may activate transcription
•The response may occur in cytoplasm