7-3: Movement
Through the Membrane
Cell Membrane
 Filter that regulates what enters and
leaves the cell while also providing
protection and support.
 Lipid Bilayer: double-layer sheet that
forms the core of almost all cell membranes
Cell
Membrane
Diffusion
 Process in which molecules tend to move from an
area where they are more concentrated to an area
where they are less concentrated.
 Concentration: mass of solute in a given volume of
solution (examples: chemical concentrations,
perfume, dosage etc.)
Diffusion

Think-Pair-Share +
Demo
 Based on what you know about diffusion,
what do you think will happen to the
molecules of this scented spray when
sprayed in this classroom?
--------
DEMO---------
 Diffusion causes substances to move
across a cell membrane but doesn’t
require the cell’s energy.
Osmosis
 Diffusion of water through a selectively
permeable membrane
 Selectively permeable membrane: some
substances can pass, others cannot pass.
 Osmotic pressure: pressure osmosis exerts on
the hypertonic side of a selectively permeable
membrane.
Effects of Osmosis
on Cells
 Isotonic: “same strength” equal concentrations
 Hypertonic: “above strength” more concentrated
 Hypotonic: “below strength” less concentrated
Facilitated Diffusion
 Movement of specific molecules across cell
membranes through protein channels.
Requires no energy.
TPS Post-It Notes
 With your elbow partner, decide what type
of transport each of these pictures belong
to:
4.
2.
1.
3.
Active Transport
 Energy-requiring process that moves material
across a cell membrane against a concentration
difference.
 Two Types of Active Transport:
1. Individual molecules are carried by using membrane
associated pumps
2. Large amounts of material are transported through
movements of the cell membrane.
a. Endocytosis: taking material into the cell by means of
infoldings, or pockets of the cell membrane
I. Phagocytosis: extensions of the cytoplasm surround and
engulf large particles.
b. Exocytosis: process by which a cell releases large
amounts of material
Endocytosis v. Exocytosis
 Animation:
http://www.youtube.com/watch?v=DuDmvlbpjHQ
Exit Ticket
Name the 5 types of
transport is the cell
membrane capable of?