The document provides instructions to divide a piece of paper into four quadrants and write answers to prompts in each quadrant, including a TV show or movie, longest street lived on, a silly word, and favorite animal.

1. Do Now –please
• Take out a piece of binder paper
• Divide into 4 quadrants
1.1. top left corner –a TV show ortop left corner –a TV show or
movie you think more peoplemovie you think more people
should watchshould watch
2.2. top right corner – Name of thetop right corner – Name of the
street you’ve lived on thestreet you’ve lived on the
longestlongest
3.3. bottom left corner – a silly wordbottom left corner – a silly word
4.4. bottom right corner – favoritebottom right corner – favorite
animalanimal
Last Week
Tonight
Amethyst WayAmethyst Way
bababooey tiger
Don’t take
too long –
these
answers
aren’t
important

2. Cell Communication

3. Overview
• Cell-to-cell communication is absolutely
essential for multicellular organisms
 Trillions of cells in a human body - there
must be a way to coordinate activities

4. Overview
• 3 steps
1.Receive a signal
2.Pass the message along inside the cell
3.Have a response to that signal

5. Overview
• Communication
is also
important in
unicellular
organisms

6. Overview
• Biologists have discovered
universal mechanisms of
cell communication
• The same small set of cell
signaling processes show
up across all life forms
 More evidence for theMore evidence for the
interrelatedness of all livinginterrelatedness of all living
thingsthings

7. Overview
• Cells most often
communicate by using
chemical signals

8. Some questions to explore
1. What messages are
passed from cell to
cell?
2. How do cells respond
to these messages?

9. An example of Cell Communication in
microbes
• Microbes like
yeast talk about
sex
• Saccharomyces
cerevisiae (yeast)
identify potential
mates using
chemical signals

10. Yeast Sex
• There are 2 “sexes”
or mating types
 a - secretes “a” factor
 α - secretes “α” factor
 These factors bind to
receptor proteins on
the other mating type

11. Yeast Sex
• Once the mating factors
have bound to the
receptors the 2 cells
grow toward each other
• The 2 cells fuse, or
mate, to form an a/α
cell
 Contains genes of
both cells
 Advantage for future
“offspring” since
have more genetic
resources

12. CRITICAL VOCAB!!
• Transduction -
the conversion of
a signal from
outside the cell
into a form that
can bring about a
specific cell
response
Message from
outside the cell
Transduction
to another
“form”
Cell
response

13. Back to yeast sex…
• Q: So how does the
attachment of the signal
molecule on the surface of
the yeast cell get
transduced into a form
that causes the cells to
fuse?
• A: by a signal
transduction pathway

14. CRITICAL VOCAB!!
• Signal transduction
pathway - a process by
which a signal on the
cell’s surface is
converted into a
specific cell response

15. Quick Think
•Discuss with a neighbor
how yeast cells
communicate in order to
mate
With your silly word
buddy

16. Signal Transduction Pathways
• They are very similar in yeast
and animal cells
 Evidence for a common ancestor
• Plants and bacteria have similar
pathways
• Evidence suggests a prokaryotic ancestor that was
capable of signaling - this organism was “adopted”
for use in single cell eukaryotes and multicellular
organisms (similar to the “adoption” of chloroplasts
and mitochondria)

17. Cell Communication in
multicellular organisms
• Communication in multicellular organisms
usually involves releasing signaling
molecules that target other cells, as we
saw in the yeast

18. Direct Contact between cells
• Recall that cells
may have
junctions that
connect
adjacent cells

19. Direct Contact between cells
• With intercellular
junctions, substances
dissolved in the cytosol of
one cell can freely pass
into the adjacent cell
• Animal cells may
communicate via
direct contact
between membrane
surface molecules
• Most often used in
development of the
embryo and during
the immune
response

20. Local contact
• Signaling cell maySignaling cell may
secrete messengersecrete messenger
moleculesmolecules
• These chemical
messages may
travel only a short
distance and
influence cells only
in the local vicinity

21. CRITICAL VOCAB!!
• Local regulators - a chemical messenger
that influences cells in the vicinity

22. Example
• Growth factors in
animals - stimulate
nearby target cells to
grow and divide
• paracrine signaling
- Many nearby target cells
receive and respond to a
local regulator that is
secreted by just one
messenger cell

23. More specialized local signaling
• Synaptic signaling -
occurs in nerve cells
• Nerve cell releases a
neurotransmitter
• It diffuses across the
synapse (small gap
between 2 neurons)
• Neurotransmitter
stimulates the target
cell
• Can also be
considered long
distance signaling
because message is
passed from neuron
to neuron over a long
distance

24. CRITCAL VOCAB!!
• Paracrine
signaling - when
numerous cells
simultaneously
receive and
respond to growth
factors produced
by a single cell in
their vicinity
• Synaptic signaling - when a
nerve cell releases
neurotransmitters into a
synapse, stimulating the
target cell

25. Local signaling in plants
• This is not well understood yet
• Must be different somehow from animals
due to presence of cell walls in plants

26. Quick Think
•With a neighbor, describe
paracrine signaling and
give an example of it
With your TV
show buddy

27. Long distance signaling
• Both plants & animals use
hormones for long distance
signaling
• In animals - endocrine cells
release hormones into circulatory
system - hormones travel to other
parts of the body
• In plants - hormones called
growth regulators - may travel in
vessels, may travel cell to cell,
may travel through the air by
diffusion

28. Long distance signaling
• Chemical messengers
vary
• Plant hormone ethylene -
very small (C2H4) - makes
fruit ripen - can pass
through cell walls
• Animal hormone
insulin - 1000s of
atoms big - regulates
blood sugar - travels
in blood stream

29. Quick Think
• Discuss with a neighbor how plant and
animal cells carry out long distance
signaling.
• Explain why nerve cells provide an
example of both local and long distance
signaling With your
street buddy

30. What happens when a cell
encounters a signal?
• The signal must be recognized by the
target cell
 Target cells have specific receptor molecules
on their cell membranes
• The information in the chemical signal
must be changed into another form -
Transduced - inside the cell before the cell
can respond

31. There are 3 stages of cell signaling
1. Reception - target cell receives chemical signal
2. Transduction - conversion of the signal to a
form that brings about a specific cell response
3. Response - the transduced signal finally brings
about a cell response

32. Quick Think
• Discuss with a neighbor:
• Summarize how cells communicate in
1 sentence.
With your
animal
buddy