Do Now:
Complete the Do Now on the Google Classroom
• Level 1
Cell Communication
SWBAT: describe how cells communicate and distinguish
between long and short-distance communication.
Independent
Reading
• For multicellular organisms,
communication between
nearby or even distant cells
is critical for the survival of
the species.
• Even single celled organisms
like bacteria have an
evolutionary advantage
when they “talk” with each
other.
There are many times when
communicating between cells is
advantageous
• Cells employ a variety of
signaling pathways in order
to send chemical messages
from cells to cell.
Model 1
Answer the questions in for Model 1 in your
worksheet
• Level 1
Cells Communicate
Using Chemical
Signals
• The sending cell (secretory
cell) secretes the signal
• The target cell responds to
the signal.
• The target cell must have
the right receptor to bind to
the ligand.
• Lock and Key
Four Categories
1.
2.
3.
4.
Autocrine (auto = self)
Juxtacrine (juxta = beside)
Paracrine (para = nearby)
Endocrine (endo = within)
The main difference between
the different categories of
signaling is the distance that the
signals travel through the
organism to reach the target.
Model 1
Answer the questions in for Problem 2 in your
worksheet
• Level 1
Autocrine Signaling
auto = self
• The cell targets itself
• Releases a ligand that binds
to its own receptors on its
own surface
• Helps cells assume correct
identities during
development.
• Plays a key role in metastasis
(the spread of cancer)
Juxtacrine Signaling
juxta = beside
• Signaling through cell to cell
contact
• Gap junctions in animals
and plasmodesmata in
plants are tiny channels that
directly connect neighboring
cells.
Paracrine Signaling
para = nearby
• Relatively short distance
• Allows cells to locally
coordinate activities with
their neighbors.
• Synaptic signaling in
neurons use ligands called
neurotransmitters.
Endocrine Signaling
endo = within
• Transmits signals over long
distances
• Hormones travel through the
blood stream to their target.
• Endocrine glands release
hormones
• Thyroid, hypothalamus,
the pituitary gland,
gonads (testes and
ovaries) and pancreas.
Secretory cells use ligands as
signals to elicit a response from
target cells.
Key
Takeaways
Four Categories of Chemical
Signaling
• Autocrine = the cell targets itself
• Juxtacrine = cell to cell contact
• Paracrine = short distance communication
• Endocrine = long distance communication
Exit Ticket
Complete the Exit Ticket on the Google Classroom
• Level 0