CELL -CELL INTERACTIONS
CH 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 specific
1. 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.mcgrawhill.com/sites/0072507470
/student_view0/chapter18
/animation__mechanism_
of_steroid_hormone_actio
n__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.mcgrawhill.com/sites/0072437316/student_view0/chapter7/animations.ht
ml
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