March
th
15
Part II
 Cellular Transport (text: 63-79)
 Notes: Passive Transport (Diffusion,
Osmosis)
 Cell Membrane Video
 Lab 8: Diffusion, Osmosis
 Osmosis Practice WS
 Notes: Active Transport
 Cellular Transport Handout
 Break
Homeostasis & Transport
Section 1: Diffusion & Osmosis
Homeostasis
 Homeostasis: the
biological balance
between a cell or an
organism and its
environment
 Cells maintain
homeostasis by
controlling and regulating
what gets into and out of
the cell.
Diffusion
 Diffusion: the process by which
molecules move from an area of greater
concentration to an area of lower
concentration
Diffusion
Brownian
Motion
 Brownian Motion: molecules are in a
constant state of random motion
Brownian
Motion
Concentration Gradient
 Concentration Gradient: the
difference in concentration of a
substance across a space
Dynamic Equilibrium
 Dynamic Equilibrium: a state that exists
when the concentration of a substance is the
same throughout a space
Dynamic
Equilibrium
Review of Cell Membrane Structure
Diffusion Across Membranes
 Not all molecules can
diffuse through all
membranes.
 The ability of a molecule
to pass through a
membrane depends on
the size and type of
molecule and the
molecular structure of
the membrane.
Small nonpolar
molecules can diffuse
through the cell
membrane
Osmosis
 Osmosis: the diffusion of water
molecules through a selectively
permeable membrane from an area of
high water concentration to an area of
lower water concentration
Osmosis
Three Types of Solutions
90% H2O
10% solute
85% H2O
15% solute
95% H2O
5% solute
90% H2O
10% solute
90% H2O
10% solute
90% H2O
10% solute
Isotonic
(no net movement
of water)
Hypotonic
Hypertonic
Three Types of Solutions
Plant Cells
Three Types of Solutions
Animal Cells
Three Types of Solutions
Cytolysis
Plasmolysis
Three Types
of Solutions
Contractile Vacuoles
 Contractile Vacuole: an organelle in
microorganisms that excretes water
 collect excess water → contract → squeeze
out water
Study the diagram below. It represents a container that is divided
by a semipermeable membrane. A different solution in its initial
state is shown on each side of the membrane.
1.
2.
3.
4.
Describe which molecule(s) will move through the
membrane and which molecule(s) will not.
Describe the relative rates at which the molecule(s) will
move across the membrane.
Describe in which direction the molecule(s) will move.
Describe how long the molecule(s) will continue to move.
Section 2: Other Kinds of Transport
Review of Cell Membrane Structure
Review of Cell Membrane Structure
Passive Transport
 Passive Transport: the movement of any
substance across a cell membrane without the
use of cell energy
 Diffusion
 Osmosis
 Facilitated Diffusion
 Gated Channel
Facilitated Diffusion
 Facilitated Diffusion: a process in
which substances move down their
concentration gradient across the cell
membrane with the assistance of carrier
proteins
 Examples: glucose, fructose, & ions
Facilitated
Diffusion
Facilitated
Diffusion
Gated Channel
 Gated Channel: a protein-lined gated
passage making cell membranes
permeable to certain large molecules as
needed
 Example: neuromuscular function
Gated Channel
Active Transport
 Active Transport: the movement of
any substance across a cell membrane
with the use of energy from ATP
 Sodium-Potassium Pump
 Endocytosis
 Exocytosis
Sodium-Potassium Pump
 SodiumPotassium
Pump: an active
transport
mechanism that
moves ions in
order to achieve
polarization
Proton Pump
 Proton Pump: an active transport
mechanism that consumes ATP
(energy) to force Hydrogen ions against
the concentration gradient
Proton Pump
Proton Pump
Endocytosis
 Endocytosis:
the process by
which a cell
engulfs and
surrounds large
substances
Endocytosis
Exocytosis
 Exocytosis:
the process
by which
wastes are
packaged in
vesicles and
leave the cell
Exocytosis
Passive vs.
Active
Transport
Passive vs. Active Transport
Diffusion Osmosis
Facilitated Gated
Endocytosis/
Pumps
Diffusion Channel
Exocytosis
Direction
High
to Low
High
to Low
High
to Low
Transport
Mechanism
Pores
Pores
Channels
Energy
Required?
No
No
No
No
Yes
Yes
Type of
Particle
small
nonpolar
water
smallmedium
smallmedium
ions
smalllarge
Examples
of Particles
CO2, O2
H2O
High
to Low
Low to
High
Gated
Pumps
Channels
Glucose, Glucose,
+
+
Na
,
K
,
Fructose, Fructose,
+
+
+2
+2
H
Na , Ca
Na+, Ca
N/A
Membrane
food, waste