Download I. The Cell Membrane: II. Three Functions of the Cell Membrane

Unit 3: Cellular Processes
Name: ___________________________________
Aim #14 Cell Membrane: How does the cell membrane function to maintain homeostasis?
I.
Date: ___________________
The Cell Membrane:
A ___________________________ thin structure that acts as a barrier to __________________ the
What is it?
_________________ of the cell from the __________________ (outside) environment
__________________________________________ or ____________________________________________
Also known as…
Which types of cells
have a cell membrane?
What is the structure?
II.
Three Functions of the Cell Membrane
1. SEPARTION & PROTECTION: ____________________ the contents of the cell from the _____________________________________
2. TRANSPORT: ________________________ the transport of ____________________ in and out of the cell
3. COMMUNICATION: _________________________ with other cells through the use of ___________________________ by sending and
responding to chemical ________________________________________
FUNCTION #1: How does the cell membrane separate the inside of the cell from
the outside of the cell?
1. The structure of the cell membrane acts as the __________________ between the _______________ and the
_______________ of the cell.
2. Keeps the _____________________ cell environment _______________________ in an environment that is
_______________________ (homeostasis)
3. The membrane is ____________________________: allows certain materials in and out of the cell based on
_________________ and _______________
FUNCTION #2: How does the cell membrane control the transport of molecules
in and out of the cell?
1. What types of molecules must ENTER the cell to
maintain homeostasis
2. What types of molecules must LEAVE the cell to
maintain homeostasis
Key Transport Terms:
 Solvent: a substance that ______________________ another substance (ex: water)
 Solute: a substance that is _______________________ (ex: sugar, salt)
 Solution: when a substance is dissolved into another substance (ex: ________________________)
 Concentration: a measure of the amount of a __________________ in a solution
Which has the greatest concentration of water? ______
Which has the greatest concentration of solute? ______
Types of Cell Transport
Type of
Transport
Definition
Which molecules?
How do molecules move?
Type of
Transport
Require ATP
from the cell?
Example

The movement of molecules
Examples of molecules moved:
= GLUCOSE
(needed by the cell to make
energy)
(solute) from areas of
1. Diffusion
___________ concentration to
areas of _________ concentration
of solute
Moves from:
__________ to _________
concentration
Examples of molecules moved:
The movement of
________________ molecules
 = SALT
Water is usually represented by the
white space
from ___________ concentration
of water to __________
2. Osmosis
concentration of water
Moves from:
__________ to _________
concentration

The process by which cells use
3. Active
Transport
Desert plants use active transport to
bring minerals from the soil, which is
at very low concentrations, and move
it into their root cells where the
mineral concentration is higher
_________ (energy) to transport
molecules through the cell
membrane from areas of
__________ concentration to
areas of ___________
concentration.
= MINERAL
Examples of molecules moved:
Moves from:
__________ to _________
concentration
A cell can be in the following types of solutions:
1. Hypertonic: solution outside of the cell has a high concentration of particles and low concentration of water
2. Hypotonic: solution outside of the cell has a low concentration of particles and a high concentration of water
3. Isotonic: solution outside of the cell has the same concentration of particles and the same concentration of water
1. Name two differences between passive (diffusion) & active transport.
2. Name one similarity between passive (diffusion) and active transport
3. Why is it important that the large organic macromolecules (such as proteins and starches) are digested before passing
through the cell membrane?
4. When the macromolecules are broken down into their building blocks, what happens to them upon entering the cell?
FUNCTION #3: How does the cell membrane recognize and respond to signals?
1. _______________________________________ are ______________________ in the cell membrane that can receive
(hormones, nerve signals) from other cells which is important for
______________________ and __________________________ between cells
2. Since receptor molecules are proteins, what can you infer about their interaction with chemical messages?
Diagram of cell membrane receptor
molecule and a chemical signal
 = Chemical message
Cell A
Cell B
 In the diagram above, which cell will be able to receive the chemical message? _____________
Explain why:
 What would happen if the cell receptor able to receive signals was denatured? _____________________________
____________________________________________________________________________________________
Practice Questions
A) Read each statement below and WRITE the correct term on each line. You can use the terms more than once!




active transport
diffusion
equilibrium
osmosis









Energy
size
passive transport
cell membrane
semi permeable
receptors
lipid
swell
shrink
1. _______________________ Is used during active transport but not passive transport
2. _______________________ Particle movement from an area of lower concentration to an area of higher concentration
3. _______________________ These are located on the cell membrane and recognizes and sends chemical signals
4. _______________________ If there is more water outside of a cell than inside of the cell, the cell will…
5. _______________________ When a membrane is selective about the materials allowed in and out of the cell
6. _______________________ The diffusion of water through a cell membrane
7. _______________________ The movement of substances through the cell membrane without the use of cellular energy
8. _______________________ If there is more water inside of a cell than outside of the cell, the cell will…
9. _______________________ The semi-permeable structure of a cell that allows molecules to move in and out
10. _______________________ When energy is required to move materials through a cell membrane
11. _______________________ When the molecules of one substance are spread evenly throughout another substance to
become balanced
12. _______________________ When molecules move from areas of high concentration to areas of low concentration
13. _______________________ The main component of a cell membrane
14. _______________________ This property determines which molecules can enter and leave the cell
B) Below each diagram, label the term that defines what is happening in each cell in the box below the image. Use the
following terms: diffusion, active transport, osmosis, equilibrium. The arrows show the direction of transport. You
may use the terms more than once!
High
CO2
levels
Low CO2 levels
25 glucose
molecules
2 H2O
molecules
8 H2O
molecules
TERM:
2 H2O molecules
TERM:
High
protein
levels
2 H2O molecules
TERM:
__________________
__________________
__________________
5 glucose molecules
Low protein
levels
TERM:
TERM:
__________________
__________________
C) Using your knowledge of biology and the images of each cell below, answer the following questions:
a. Draw an arrow to show the passive transport of salt (NaCl) through
this cell’s membrane
1.
5% NaCl
95% H2O
95% NaCl
b. Draw a dotted arrow to show the direction of osmosis
5% H2O
c. Water will flow _____________________ (into the cell, out of the
cell, in both directions).
d. The cell will ______________________ (shrink, burst, stay the same).
e. Is this movement active or passive transport? ___________________
2.
f.
12% Cl
g. In what direction will chlorine (Cl) move after the cell dies? Explain
3% Cl
3.
90% NaCl
15% H2O
Does this movement require energy? __________________________
why! (Hint: can a dead cell make energy…?)
h. Draw an arrow to show the passive transport of salt (NaCl) through
this cell’s membrane
10% NaCl
i.
Draw a dotted arrow to show the direction of osmosis
75% H2O
j.
Water will flow _____________________ (into the cell, out of the
cell, in both directions).
k. The cell will ______________________ (shrink, burst, stay the same).
4.
a)
Does this cell show active or passive
transport? Explain WHY
b) Name two differences between active
transport and diffusion