SECTION
CELL MEMBRANE
3.3
Study Guide
KEY CONCEPT
VOCABULARY
The cell membrane is a barrier that
separates a cell from the external
environment.
cell membrane
selective permea bility
phospholipid
re ce
MAIN IDEA: Cell membranes
ptor
fluid mosaic model
are composed of two phospholipid layers.
1. Draw a phospholipid in the box below. Label the three major parts.
Phosphate group;
glycerol;
fatty acid
c
o
o
E
o
O
.c
+
=co
phospholipid is charged, or polar? the charoed oh OS o hate and qlvcerol
2.
Which part of
a
3.
Which part of
a phospholipid is nonpolar?
4.
What type of molecules interact with water, polar or nonpolar?
5. Where
the fattv acid tails
does a cell membrane come into contact with water?
G. 'Why do the phospholipids surrounding the ceil fbrm
a
ar
outside the cell
bilayer? the polar heads interact with water
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A cell membrane has other types of molecules embedded in the phospholipid bilayer. List
function of each type of molecule in the table below.
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o
U
o
o
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o)
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Molecule
Function
7. Cholesterol
strengthen the cell membrane
8.
Proteins
nelp malenals cross tne memDrane, part oï cytosKeleton
9.
Carbohydrates
help rdentrly cell types
Unit 2 Resource Book
McDougal Littell Biology
Study Guide
I
Name
Period
Date
STUDY GUIDE, CONTINUED
1O. In what way is a membrane fluid?
The phospholipids in each laver can move from side to side past each other,
11. Draw a picture in the box below to represent selective permeability.
outside
inside
Refer to figure 3.18 for visual awnser
MAIN IDEA: Chemical
signals are transmitted across the cell membrane.
12. A receptor
detects a signal molecule and carries out an action in response.
13. A ligand
is a molecule that acts as a signal when it binds to a receptor.
14. A ligand that can cross
15. A ligand that cannot
the cell membrane can bind to an
intracellular
receptor
>
c
o
cross the cell membrane can send a message to a cell by binding to
membrane
receptor, which then
Ghanges
oE
o
shape.
.ç
Ë
Vocabulary Gheck
=co
c
16. What is the fluid mosaic model?
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the fluid mosaic model is a description of the arrangement of the molecules that make up a cell mem bran6E
J
17. The cell membrane allows some, but not all, molecules to cross. What term describes
this property?
selective permeability
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Study Guide
Unit 2 Besource Book
McDougal Litlell Biology