Download Cell Communication Part I

Warm-Up (12/07)
On the piece of white paper from the back, answer
the following question.
No Warm-Up!
Get working on your
test! You have 20
minutes exactly!
Name
Date
Period
Cell Communication
Cells communicate using signals (aka ligands)
Ligand binds receptor at
surface of cell
Receptor changes shape,
activating second
messengers
Second messengers
change cell activities
and/or affect gene
expression
Cell Communication
Signal transduction: when
a ligand causes a cellular
response
genes to be
expressed
http://www.wiley.com/legacy/college/boyer/0470003790/animations/signal_transduction/signal_transduction.htm
Cell Communication
Like an enzyme to a
substrate, a receptor only
recognizes a specific ligand
ligand
receptor
before
after
Cell Communication
For example, G Protein-Coupled
Receptors (GPCRs) activate G
proteins as secondary messengers.
Cell Communication
Signaling cascades are chains of secondary messengers.
Each one activates
the next by
modifying it:
for example,
phosphorylation
(putting on a
phosphate).
Cell Communication
Usually, the ultimate goal is turning on and/or off genes.
For example, ethylene ripens fruit.
nucleus
P
unactivated
receptor
2nd messenger
enzyme genes
activated
ethylene
(ligand)
P
receptor
2nd messenger
enzyme genes
Critical Thinking Question #1
Discuss this question with your partner and write or
represent it. I will call on three people to share their
partners’ answers.
Describe the molecular nature of a chemical
signal and explain the key elements of a
signal transduction pathway responsible for
causing a cellular response. How do
concentration levels of signal affect the
cellular response?
Closure
On the piece of white paper from the
back, answer the following question:
Explain how a specific cellular
signal can promote production of a
specific protein.
Name
Date
Period
Scale
1 – 10