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