CELL MEMBRANE AND
CELL TRANSPORT NOTES
CA Standard
Cell Biology
1. a. Students know cells are enclosed
within semipermeable membranes that
regulate their interaction with their
surroundings.
What is the cell membrane?
The cell membrane regulates what enters
and leaves the cell and also provides
protection and support.
The structure of the cell membrane
 The cell membrane
consists of a lipid bilayer
(lipid = fat; bi=2) plus
proteins that straddle the
bilayer. Attached to the
proteins are
carbohydrates.
 Many of these proteins are
channels and pumps that
allow substances through
or not!
Draw the cell membrane, color and
label it. (p.182)
Cell Membrane
You should be able to answer these
questions:
1.
2.
3.
4.
5.
Describe the structure of the cell membrane.
How do molecules get into and out of the cell?
What is selective permeability?
What is diffusion and how does it work?
What is facilitated diffusion and how does it
work?
6. What is active transport and how does it work?
7. What is osmosis and how does it work?
8. What is the function of transport proteins?
Transport through the Cell
Membrane
Cell membranes are selectively
permeable (semipermeable).
Permeable- ability to pass through a
membrane
Impermeable- can’t pass through
Selectively Permeable (semipermeable)some things can pass through and some
can’t
Copy the chart into your notes
Type of
Transport
Simple
Diffusion
Facilitated
Diffusion
Active
Transport
Transport
Protein
Used?
Direction of
movement
Requires
Classification
Energy
of
input
transport?
from cell?
Types
of
Subst
ances
Transport Through the Membrane
 Simple
Diffusion
 Facilitated
Diffusion
 Active
Transport
Simple Diffusion
No transport protein used
Movement WITH the
concentration gradient
(high to low)
No additional cell energy
required
PASSIVE
Examples: water, carbon dioxide
and oxygen
Type of
Transport
Transport
Protein
Used?
Direction of
movement
Simple
Diffusion
NO
With
concentration
gradient
(high to low)
Facilitated
Diffusion
Active
Transport
Requires
Classification
Energy
of
input
transport?
from cell?
NO
PASSIVE
Types
of
Subst
ances
WATER,
CO2, O2
Solution- a liquid with one or more
substances dissolved in it
Solvent- the liquid that the solute is
dissolved in
Solute- the substance dissolved in a
solution
Concentration- how strong it is  the
solute/volume (percentage)
Think of living cells like little bags of
solutions surrounded by a
semipermeable membrane!
For the cell to survive, the
concentration of solutes must stay
within a safe range to maintain
homeostasis.
Concentration Gradient- when
there is a difference in
concentrations
High concentration: more particles
Low concentration: fewer particles
In diffusion, particles move from high to
low concentration to reach an equal
concentration (equilibrium) on each side.
Facilitated Diffusion
Transport protein used: carrier protein or
channel protein
Movement WITH the concentration
gradient (high to low)
No additional cell energy required
PASSIVE
Example: Glucose molecules
Type of
Transport
Transport
Protein
Used?
Direction of
movemen
t
Simple
Diffusion
NO
With
concent.
gradient
Facilitated Yes:
With
Diffusion Channel
concent.
Proteins or gradient
Carrier
Proteins
Active
Transport
Classification
of
transport?
Types
of
Subst
ances
NO
PASSIVE
WATER,
CO2, O2
NO
PASSIVE
GLUCOSE
Requires
Energy
input from
cell?
Carrier Proteins
Channel Proteins
Passive Transport: Facilitated Diffusion
Active Transport
Transport protein used: carrier protein
Movement AGAINST the concentration
gradient (low to high)
Additional cell energy required
ACTIVE
Example: Sodium-Potassium Pump:
pumps Na+ ions out of cell and K+ ions
into cell
Classification
of
transport?
Type
of
Subs
tanc
e
NO
PASSIVE
WATER,
CO2, O2
With
concent.
gradient
NO
PASSIVE
GLUCOSE
Against
concent.
gradient
YES
ACTIVE
Na+ and
K+ ions
Type of
Transport
Transport
Protein
Used?
Direction of
movement
Simple
Diffusion
NO
With
concent.
gradient
Facilitated
Diffusion
Yes:
Channel
Proteins
or Carrier
Proteins
Active
Yes:
Carrier
Proteins
Transport
Requires
Energy
input from
cell?
Active Transport
Active Transport
Other Types of Active Transport
Endocytosis – the process of taking
material into the cell by folding in pockets of
the cell membrane into pouches called
vesicles
Phagocytosis – endocytosis involving large solid
particles
Pinocytosis – endocytosis involving liquid
Exocytosis – the process of removing
material out of the cell where vesicles merge
with the cell membrane to release contents
Endocytosis and Exocytosis
Osmosis- the diffusion of water
No transport protein
used
With the
concentration
gradient (high to low)
No additional cell
energy required
Passive
Concentration Strength
Isotonic – the solution and the cell have the
same concentration strength
Hypotonic – the solution has a lower
concentration than the cell
Hypertonic – the solution has a higher
concentration strength than the cell
Osmotic Pressure
Osmotic Pressure is the pressure that
water exerts on the hypertonic side of a
selectively permeable membrane.
It can be problematic for living cells
because they can burst from over-inflation
with water or shrivel up from loss of water.
Red Blood Cells in a
Hypertonic Solution
Plants and Osmosis
Applications of Osmosis
Water overdose/intoxication
Penicillin kills bacteria
High concentration of fertilizer kills plants
Water enters the roots of plants
Why drinking salt water can kill you
Why putting salt on a slug or snail kills it
How dialysis machines work
The preservation of foods in salt brines (olives,
fish vegetables)  kills bacteria
Desalination works by reverse osmosis
Refresh wilted salad greens by putting in water
Osmosis Worksheet
10 points
Diffusion and Osmosis in Living
Systems
40 pts
Cell Quiz
1.
2.
What are two differences between prokaryotes and eukaryotes?
An animal cell is a prokaryotic/eukaryotic cell. (circle the correct
answer)
3. When preparing a wet mount, the cover slip should be put on at an
angle to avoid ______.
4. The ______ contains the DNA and controls the cell.
5. Diffusion is the movement of molecules from a ______ to a _______
concentration.
6. If a cell has 95% water and it is placed in a hypertonic solution, water
will move out of/into the cell. (circle the correct answer)
7. _________ are where photosynthesis occurs in plant cells.
8. A bacteria is a prokaryotic/eukaryotic cell. (circle the correct answer)
9. On high power, more/less of the cell can be seen. circle the correct
answer)
10. What two things happen to an image when viewed under a
microscope?
11. Choose and explain one of the following: endocytosis, phagocytosis,
pinocytosis, or exocytosis.