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Cell Specialization &
Communication
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WRITE QUESTION AND ANSWER!
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What are the first cells?
What are the two types of cells?
Which one is MORE desirable?
Why is it more desirable to scientists?
Where do cells come from?
• Multicellularorganisms begin as
undifferentiated masses of cells.
• This means that they do not yet have specific
jobs yet!
• These cells are known asSTEM CELLS.
What are two types of stem cells?
• Embryonic Stem Cells
• Adult Stem Cells
What are EMBRYONIC stem cells?
• Embryonic cells which have not yet
differentiated (changed) into different cell
types
• Form soon after the egg and sperm meet!
• Embryo = a fertilized egg that is in the
beginning stages of a pregnancy
What are ADULT stem cells?
• Adult Stem Cells: stem cells found in
organisms, such as in bone marrow
• The adult stem cells can only become the type
of cells in the part of the body where they are
found
– Ex.: stem cells found in the bone marrow can only
become bone marrow cells
BrainPop
http://www.youtube.com/watch?v=jF2iXpoG5j8
How can different cells perform different
functions if all cells have the same genes and
DNA?
• All cells have the SAME DNA
• BUT, cells have different JOBS
• This is because of the expressionof the genes
in their DNA (what is ‘turned on’)
What is GENE EXPRESSION?
• An expressed gene is a gene that is ‘turned on’ to
create proteins.
• Those cells that are not expressed remain “silent”
• Cells have different jobs based upon which genes
are turned ON and which are turned OFF
• Not all the genes are being used at all times
• Also called GENE REGULATION
How is GENE EXPRESSION like a
PIANO?
• Every piano has the same set of keys
– Just like every cell has the same DNA
• The piano keys can play different songs
depending on which keys are played
– Just like different cells are able to perform
different functions (jobs) depending on the genes
that are “chosen” to be expressed or “played”
How does an organism know when to turn a
gene on or off?
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Environmental influences
•
Different genes are expressed depending on the
environment of the cell.
• Ex. E. coli bacteria in the human stomach
– E. coli feed on lactose (a sugar found in milk)
– When the sugar is present in your stomach, certain genes are
turned on, or expressed, so the bacteria can digest lactose
– When nosugar is present, those genes remain silent (OFF) and no
proteins are created (because the proteins are not needed)
What is CELL SPECIALIZATION?
• Different genes are expressed depending on
the specific job of the cell
• This creates different types of cells (muscle
cells, nerve cells, sperm cells, etc.)
– Ex. Keratin
• Keratin is a protein that produces hair.
• The genes that produce keratin are expressed (ON) in
skin cells but remain silent (turned OFF) in blood cells
What can happen if the genes are
turned ON or OFF at the wrong time?
• Making the wrong proteins can ruin your
body, and even your life.
• Cancer: proteins are created at the wrong
time, which causes uncontrolled cell
reproduction leading to tumors that may
cause cancer (genes are always turned ON)
Stem Cell and Gene Regulation
Stations
• Station 1: Brainpop
– With your group, watch the Brainpop video loaded on the computer
– Feel free to pause when needed to record to answers to the Viewing
Guide
• Station 2: Practice Questions
– Work with your group to complete the practice questions. Use each
other and your notes
• Station 3: Definition Boards
– Work with your group to complete the Definition Boards for STEM
CELLS and GENE EXPRESSION
– Follow the directions for what to answer in each box
CELL SPECIALIZATION!!
Sperm Cell
• Function:
– A sperm cell swims rapidly to
an egg during reproduction.
• Adapted For:
– SWIMMING!
– A sperm cell has a tail, or flagellum to allow it to
swim to meet the egg.
– LOTS of MITOCHONDRIA needed!
Red Blood Cell
• Function:
– A red blood cell carries necessary oxygen to cells
and carbon dioxide that is released away from
cells.
• Adapted For:
– CARRYING!
– A blood cell looks like a bowl because it has to
carry molecules to and from cells.
Muscle Cell
• Function:
– A muscle cell stretches and
contracts to allow the body to move.
• Adapted For:
– STRETCHING!
– Muscle cells are long and flat to allow them to relax
and contract.
• When muscle is being used it is contracting and when a
muscle is not being used it is relaxing.
– LOTS of MITOCHONDRIA needed!
Nerve Cell
• Function:
– A nerve cell transmits (sends) messages to other
cells
• Adapted For:
– FAST COMMUNICATION!
– Nerve cells send signals called HORMONES
(proteins) to communicate with other cells.
Xylem Cell
• Function:
– A XYLEM cell transports water and minerals from
the roots to the leaf of a plant. .
• Adapted For:
– QUICK MOVEMENT OF WATER!
– Xylem cells only transport water and minerals in
one direction UP from the root to the leaves and
top parts of the plant.
Phloem Cell
• Function:
– A PHLOEM cell transports food and
nutrients from the leaves to storage organs and growing
parts of the plant.
• Adapted For:
– QUICK MOVEMENT OF FOOD!
– A PHLOEM cell moves food and nutrients from the
leaves to other parts of the plant,
• because the food is being made in the leaves by
photosynthesis and stored in other parts of the plant for
future use.
Cell Specialization Stations
• Station 1: Cell Meet-and-Greet
– With your group, you will each play a role as a cell
– Introduce yourself to your group and share your key details
– Record the details of the Cell introducing themselves
• Station 2: Practice Questions
– Work with your group to complete the practice questions. Use each
other and your notes to complete.
• Station 3: Cell Specialization Foldable
– Work with your group to complete the Cell Specialization foldable
– Use the INTRUCTION & RUBRIC sheet and your notes to complete
CELL COMMUNICATION!!
CELL COMMUNICATION
All cells have to communicate to help
an organism survive! There are TWO
ways they do this…
HORMONES
• Proteins used for communication between cells
• SHAPE MATTERS! Only works for cells with the right
RECEPTOR proteins
– Just like theEnzyme LOCK-and-KEY Model – if the shape
doesn’tfit then themessage does NOT get delivered!
• TravelSLOWLY
– SLOWER type of communication when
compared to NEURONS
• In plants AND animals
NEURONS
• Send out molecules called NEUROTRANSMITTERS to
communicate between cells
• Found in the Nervous System (the brain
and spinal cord!)
• Travel QUICKLY!
– FASTER type of communication
• InANIMALS only
– How to remember this…plants
don’t have a brain or spinal cord
WHAT IF…
What would happen to a city if the
population grew rapidly, but the city
infrastructure did not expand?
(Example: the streets stayed the same
size…)
Cells must DIVIDE!!
• Once a cell gets too big it can no longer do all of
the jobs it needs to do.
• Just like traffic in a city that has grown faster than
the roads…
– There is too much traffic going in an out of the cell
and the cell becomes inefficient
– That means, the proteins your body desperately needs
(and quickly!) get stuck in traffic jams and don’t get to
where they need to go on time
How does this happen?
• Surface area vs. volume
• The volume (stuff inside the cell) grows faster
than the surface area (the cell membrane) that is
responsible for letting things in and out.
• If things cannot efficiently get in an out, the cell
stops functioning properly
• SO IT MUST DIVIDE!!
Check Point
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Why do cells divide?
What would happen if cells did not divide?
What are the two ways cells communicate?
Explain what can happen if materials cannot
efficiently get in and out of the cell?
5. What are two ways cells communicate?
6. Which of the two types travels more slowly?
7. Which type of communication is only found in
animals?
Cell Communication Stations
• Station 1: Hormone vs. Neuron comparison
• Station 2: Practice Questions