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Cell Transport Notes
More about the Plasma Membrane
___________________________________ - means that the plasma membrane only allows certain things through.
3 main molecules found in the plasma membrane (0ther than lipids):
1. ________________________
2. ________________________
3. ________________________
Demonstrations:
1. What happened when Mrs. Brougher sprayed febreeze at the front of the room?
2. What do you think will happen to the food coloring in the water? (circle one)
stay in the same place / spread throughout the water quickly / spread throughout the water slowly
3. What did happen?
4. What is this process called? ________________________
Diffusion & Osmosis
2 types of transport are PASSIVE and ACTIVE.  Circle which one we are talking about first.
Passive Transport
When molecules pass through the cell membrane with ______________________________________________
Diffusion Concentration Gradient

Molecules naturally move from areas of __________ concentration to areas of __________ concentration

We call this moving __________ the _______________________________________
Let’s Draw: Draw a picture of molecules moving down their concentration gradient. Label the membrane and
use an arrow to show direction of movement.
Things that affect rate of diffusion:
1.
2.
3.
Cell Transport Notes
The diffusion of _____________________ across a selectively permeable membrane is called _____________________
The regulation of water through the plasma membrane is important for the cell to maintain _______________________
Solute –
Solvent –
What controls osmosis?
Water will flow to the side of the membrane where _________________________________________________________
Water diffuses until it is in _____________________ concentration on __________________________________________
Water is polar. Phospholipids are nonpolar. How can water move through the membrane? __________________________
What cell part helps to pump water out of a plant cell? ______________________________________________________
3 Osmotic States:
1. ___________________ – solute concentration outside of the cell is the same as the concentration inside the cell
a.
Where is most of the water located in an isotonic solution??
inside cell
outside cell
equal on both sides
b. Are water molecules moving into and out of the cell??? ________________________________________
c. A plant cell has its _____________________ shape and pressure in an isotonic solution.
2. ___________________ – solute concentration is lower in the solution outside the cell than the concentration
inside the cell, so water moves INTO the cell.
a.
Where is most of the water located in a hypotonic solution??
inside cell
outside cell
equal on both sides
b. What happens if the cell swells too much ??? __________________________________________
i. This can occur in (circle one):
plant cells
c. Example: veggie section in grocery store
animal cells
both plant and animal cells
Explain:
3. _____________________ – solute concentration of outside the cell is higher than the concentration inside the
cell, so water moves OUT OF the cell
a.
Where is most of the water located in a hypertonic solution??
inside cell
outside cell
equal on both sides
b. Animal cells in a hypertonic solution _____________________ because of decreased pressure in the
cells.
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Cell Transport Notes
Carrot Demo:
Background – carrots were soaked in a saltwater solution overnight. Students will examine the carrots and
determine what type of solution the saltwater is based on carrot characteristics.
1. Describe your carrot. How are these carrots different from normal carrots?
2. Consider the salt water solution. What is the solute? The solvent?
3. Before the carrots were placed in the water, where was the concentration of salt higher – inside the carrot cells,
or in the surrounding water?
4. Were the carrots in a hypo-, hyper-, or isotonic solution? How do you know? (circle one, explain)
a) Hypotonic
b) Hypertonic
c) isotonic
How do you know?
5. Explain why putting carrots in freshwater keeps them firm. Use the terms hypotonic and concentration
gradient in your answer:
Starch/Iodine Experiment
Background – iodine is an indicator and will turn purple in the presence of starch. The baggie is a barrier between
the starch and iodine, and we are testing to see if the baggie is permeable to either starch or iodine molecules.
Also: starch molecules are relatively large, while iodine molecules are relatively small.
Make a prediction: (circle one)
1. The starch will move out into the beaker
2. The iodine will move into baggie
3. Neither starch nor iodine will move
-
How will we be able to tell if either moves?
-
In this mini-lab, what cell part does the baggie represent?
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Cell Transport Notes
Analysis:
1. Which moved – the iodine or the starch? (circle one)
iodine
starch
a. Explain how you know:
2. Draw a picture of the cup and baggie. Label the molecules and use arrows to show which way the diffusion
occurred:
Facilitated Diffusion
-
What are some molecules that need no energy to move?
-
What does it mean to ‘facilitate’?
__________________________________________ help substances move through the plasma membrane.
No energy is needed because the molecules are moving _____________________________________________________
Facilitated diffusion –
Two main types of proteins:
1. ______________________________________ change shape to allow a substance to pass through the plasma
membrane.
2. ______________________________________ form channels that allow specific molecules to flow through.
(do not change shape)

In facilitated diffusion by carrier protein, the movement is __________ the concentration gradient and requires
__________ input from the cell.
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Cell Transport Notes
Active Transport
 What molecules WOULD require energy to pass through the plasma membrane?

Movement of materials through a membrane ___________________________ a concentration gradient is called
_____________________ _____________________ and requires _________________________________________

In active transport, a transport protein called a ___________________________________ first binds with
___________________________________________________________________________
VIDEO  An example of active transport is the ____________________________________________________________
What is the energy molecule that is used in the sodium-potassium pump? ____________
How active transport works:

Each type of carrier protein has a shape that ______________________________________________.

When the proper molecule binds with the protein, the cell _______________________________________ of the
carrier protein so that the particle to be moved is _______________________________________________________

Once the particle is released, ________________________________________________________________________
Transport of large particles
1. _____________________ is a process by which a cell surrounds and takes in ______________________________
a. The material is engulfed and enclosed by a portion of the cell’s __________________________________
b. The resulting ___________________ with its contents moves ___________________________________
c. 3 types of endocytosis are:
1. _________________________________
2. Pinocytosis
3. _________________________________
2.
_____________________ is the ____________________ of materials from a cell.
Endocytosis and exocytosis both ____________________________________ and both require _____________________
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Cell Transport Notes
Passive & Active Transport – Overview
Type of
Transport
Type of transport
protein used
Up or down the
concentration
gradient?
Does it require
energy input from the
cell? (yes/no)
Is it passive or active
transport? (P/A)
Simple
Diffusion
Facilitated
Diffusion
Active
Transport
Review Questions:
1. The diffusion of water across a selectively permeable membrane is called __________________.
2. What is the expected result of having an animal cell in a hypertonic solution?
3. A grocer mists the celery display with water to keep it looking fresh. What type of solution is the celery now in?
__________________
4. Transport of materials across the plasma membrane that does not require energy from the cell but does use
transport proteins is called _________________________________.
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Cell Transport Notes
Cell size is limited
Two factors that limit cell size:
1.
2.
As a cell’s size increases, its _________________ increases at a much faster rate than its _________________________.
If cell size doubled, the cell would require 8 times more nutrients and would have 8 times more waste to excrete.
The surface area, however, would increase by a factor of only 4.
Therefore, cells cannot grow to infinite sizes, because they would either starve to death or be poisoned by wastes.
Transport Review
facilitated diffusion
endocytosis
passive transport
concentration gradient
water
sodium-potassium pump
1. In this process a protein helps move molecules across the plasma membrane without the use of
energy.
________________________________________
2. Osmosis is the diffusion of what across a cell membrane?
________________________________________
3. A cell uses energy to move molecules from regions of lower concentrations to areas of higher
concentrations by what process?
________________________________________
4. Which of the following is not a form of passive transport?
________________________________________
5. The energy-requiring process of bringing in molecules from the external environment is called what?
________________________________________
6. What determines the direction that molecules move during the process of diffusion?
________________________________________
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Cell Transport Notes
7. Why do cells expand when placed in pure water? Use the terms hypotonic, osmosis, solute, and
concentration gradient to answer.
8. Choose one of the following demonstrations and explain (in full sentences) what happened using at
least 3 of the terms from the box below.
diffusion
osmosis
concentration gradient
energy
hypotonic
hypertonic
a. Mrs. Brougher sprayed the perfume at the front of the room
b. Carrots were left in salt water overnight
c. Starch solution was placed in a baggie and then in a beaker with iodine
Which demo are you explaining? _________
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Cell Transport Notes
Transport Review Homework
Complete the paragraph below by circling correct words and filling in the blanks. Use the word bank at
the bottom of this page to fill in the blanks. When you come to words in bold, choose the best word and
circle it. You’ll need to refer to your notes for this exercise.
There are two categories of cell transport: passive transport and active transport. Passive
transport requires energy/no energy. One type of passive transport is called ____________.
In this process molecules move directly through the plasma membrane up/down the
concentration gradient. This requires energy/no energy. Another type of passive transport
is ____________. This is when water diffuses through the membrane, up/down the
concentration gradient, and needs energy/no energy. In facilitated diffusion, molecules also
move through the membrane up/down the concentration gradient but require help from
_________________________. Because diffusion, osmosis, and facilitated diffusion all move
molecules up/down their concentration gradients and require energy/no energy, they are all
considered forms of passive/active transport.
Active transport is the movement of molecules up/down their concentration gradient, and
this process needs energy/no energy. Active transport also uses carrier proteins to move
molecules across the membrane. Carrier proteins ________________________ to move
molecules. An example of active transport is the __________________________________,
which moves sodium and potassium into and out of the cell. We know this is active transport
because it needs energy/no energy and moves both sodium (Na+) and potassium (K+) ions
up/down their concentration gradients. Another example of active transport is
________________________, which moves large molecules into the cell by either
phagocytosis, pinocytosis, or receptor-mediated phagocytosis. The process of removing
waste from the cell is called ________________________. Both endocytosis and exocytosis
move large molecules and both need energy/no energy to do this.
Cells can/cannot grow to very large sizes. This is because the inside of the cell grows faster
than the outside of the cell. However, there are several ways that cells maintain homeostasis.
These are thermoregulation, __________________________________, and oxygen regulation.
water regulation
endocytosis
osmosis
carrier proteins
diffusion
change shape
sodium-potassium pump
exocytosis
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