Class:
(
Name:
)
Date:
3 Movement of substances
across cell membrane
3.1
A

Cell membrane
(Book 1A, p. 3-3)
Structure of the cell membrane
(Book 1A, p. 3-3)
Singer and Nicolson proposed the (1) ______________ _______________ _______________
(流動鑲嵌模型)
-
in 1972, which suggests that:
the cell membrane is mainly made up of (2) _______________ (磷脂) and
(3) _______________
-
phospholipid molecules are arranged in a (4) _______________ and protein molecules
are (5) _______________ (散佈) among them.
protein molecules
carbohydrate molecule
outside of cell
glycoprotein
(糖蛋白)
phospholipid
bilayer
inside of cell
(cytoplasm)
protein molecules
▲ The fluid mosaic model of the cell membrane
Meaning
Fluid
Phospholipid molecules can move (6) ______________ (橫向地).
Mosaic
Protein molecules are interspersed among the (7) _______________ molecules in
a mosaic pattern.
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1
Phospholipids

Phospholipids are a type of lipid. Their structure is similar to that of triglycerides except one
of the fatty acid molecules is replaced by a (8) _____________ _____________ (磷酸鹽基團).
Triglyceride molecule
Phospholipid molecule
phosphate
group
one glycerol molecule
three fatty acid molecules

two fatty acid molecules
Features of a phospholipid molecule:
Phosphate group
Fatty acid
 (9) ______________ (Polar / Non-polar)
 (12) ______________ (Polar / Non-polar)
 Forms the (10) _______________ ‘head’
 Forms the (13) _______________ ‘tails’
 (11) _____________ (Attracted / Repelled)
 (14) _____________ (Attracted / Repelled)
by water molecules

glycerol
by water molecules
Arrangement of phospholipid molecules in the cell membrane:
outside of cell
The (15) _____________
heads face the aqueous
environment inside and
outside of cell.
The (16) ___________
tails point inwards.
inside of cell
▲ Phospholipid molecules arranged in a bilayer
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Proteins

Some proteins are attached to the surface of the phospholipid bilayer, some are
(17) _______________ half-way in the bilayer and others (18) _______________ the entire
bilayer.

Carbohydrates are attached to some proteins to form (19) _______________, which may act
as antigens or receptors.
Membrane protein
Function
I
Channel protein
a
Involved in active transport to carry substances across the membrane
II
Carrier protein
b
Receives chemical messengers (e.g. hormones) outside the cell
III
Antigen
c
Provides channels across the membrane for transporting certain ions
and small, polar molecules
IV Receptor
V
d
Speeds up reactions in the cell
e
For cell recognition (識別)
I: (20) _______________
II: (21) _______________
IV: (23) _______________
V: (24) _______________
B
Enzyme
III: (22) _______________
How is the membrane structure related to its properties and
functions? (Book 1A, p. 3-6)
small, non-polar
molecule
small, polar
molecules and
certain ions
large molecule
outside of cell
inside of cell
channel
protein
carrier protein
▲ Different substances move across the cell membrane along different paths
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Structure of cell membrane
 The cell membrane is mainly
made up of (25) ______________
and (26) _______________.
 The phospholipid molecules are
arranged in a (27) ____________.
 Some protein molecules act as
channels or carriers.
 The phospholipid molecules can
Property and function
 This makes the cell membrane (28) ____________
permeable.
 Only small, (29) _____________ molecules can
move across the phospholipid bilayer.
 Small, (30) _____________ molecules and certain
ions can move across the membrane through
channel proteins or carrier proteins.
 This makes the cell membrane (32) ___________,
move laterally, i.e. the cell
so that it can change its (33) _____________ and
membrane is (31)______________
fuse during phagocytosis and cell division.
in nature.
 (34) _______________ molecules
are interspersed among the
 This makes the cell membrane strong enough to
(35)_____________ the cell contents.
phospholipid bilayer.
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