Transcript THINK!

Cell Transport
How is material transported into
and out of the cell?
Cell Transport in the Garden
• As you observe and illustrate your
plants, think about how water and
minerals enter the plant.
• Write you ideas on the space provided.
Class Activity
Describe how we move through
out the classroom.
Class Activity Recap
The students moved from an area of high/low concentration or density to an area of high/low
concentration until ________________________ is reached.
Cell Membrane
•
The cell membrane regulates what substances can enter and
exit the cell. It is referred to as “selectively permeable.”
•
THINK! - What does selective mean?
•
•
Very Choosy
THINK! - What does permeable mean?
•
To pass through
•
Substances that can easily pass through the cell membrane are
oxygen, carbon dioxide, and water. However, other substances
such as salts and large sugar molecules can not easily pass
through.
•
Substances can move into and out of the cell by either passive
transport or active transport. Passive transport does NOT
require energy. Active transport requires energy.
Perfume Demo
• Raise your hand when you smell the
perfume!
• THINK! - How were the people in the back of
the room able to smell the perfume?
Food Dye Demo
• Observe the food coloring as it is dropped
into the beaker of water.
• THINK! - What happened to the food
coloring particles?
Passive Transport
• You just observed 2 examples of diffusion. Now,
turn to your neighbor and try to define the term
“diffusion.”
• Diffusion: the movement of molecules from an area
of HIGH concentration to an area of LOW
concentration without using energy.
The molecules will continue to move until they
spread out evenly. This is called equilibrium.
• THINK! - Can you come up with any other examples?
Diffusion Animation
• Cells obtain certain particles through diffusion. For
example, small oxygen molecules can easily pass through
the cell membrane.
• Check out these 3 animations!!
• How Diffusion Works http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_
diffusion_works.html
• Perfume Diffusion
http://www.biosci.ohiou.edu/introbioslab/Bios170/diffusion/Diffusion.
html
• Diffusion with arrows
http://www.indiana.edu/~phys215/lecture/lecnotes/diff.html
Lab Observations
Object
Prediction for
water
Raisin
Carrot
Potato
Gummy bear
Why did this happen?
Result for water
Prediction for
saltwater
Results for
saltwater
Passive Transport
• Just like oxygen and other small particles
can diffuse into and out of cells, water can
also diffuse!!
• THINK! - Can you define osmosis?
• Osmosis: the movement of water molecules from an
area of HIGH concentration to an area of LOW
concentration without using energy.
The molecules of water will continue to move until
they spread out evenly.
Raisin Demo
• THINK! - Using what you know about
osmosis, what will happen to these
raisins if I drop them in a beaker of
water? Let’s make a hypothesis!
Osmosis Problems
• Problem #1 – A cell is placed in water that contains
a little bit of salt. Therefore, the concentration of
water is higher in the beaker compared to the
inside the cell. Which way will the water flow?
ANSWER: Water will flow into the cell; the cell will swell
Osmosis Problems
• Problem #2 – A cell is floating in water that
contains a lot of salt. Thus, the concentration of
water in the beaker is low compared to the inside
of the cell. Which way will the water flow?
ANSWER: Water will flow out of the cell; the cell will shrink
Osmosis Problems
• Problem #3 – A cell is floating in fresh water. Thus,
the concentration of water in the beaker is the
same as the concentration of water inside of the
cell. Will water move into or out of the cell?
ANSWER: Water molecules will flow into and out of the cell
at an equal rate; the cell shape will remain the same
How would you explain this cartoon using
your knowledge of osmosis?
Active Transport
• Active Transport: the movement of
particles from an area of LOW
concentration to an area of HIGH
concentration with the use of energy.
• Active Transport is like pedaling a
bike uphill. Its takes a lot of energy.
• THINK! - How is active transport
different from passive transport?
• Active transport requires energy
while passive transport does not.
• **LOW to HIGH**
Osmosis in Elodea cells
• Fresh Water
• Salt Water