Download Cellular Transport

Cellular Transport
In or Out?
1. What are some things that can pass through a
window screen?
2. What are some things that can not pass through a
window screen? Why is it important to keep these
things from moving through the screen?
3. How is a window screen similar to a cell membrane?
4. Why is it important to regulate what moves into and
out of the cell?
The Cell Membrane

Selectively permeable (semi-permeable)
allows only certain substances to pass
through cannot control the movement of water
Cell membrane
The Cell Membrane
Double layer of lipids with proteins scattered throughout
Protein
Carbohydrate
chain
Lipid
bilayer
Hydrophilic
head
hydrophobic
tail
Protein
The Cell Membrane

The cell membrane helps to maintain
homeostasis

Homeostasis- maintaining a stable
internal environment even though
external conditions change
Passive Transport


No energy is required
Diffusion, Osmosis, and facilitated
diffusion are types of passive
transport
Diffusion



Particles move from an area of high
concentration to an area of low concentration
Moves “down” or “with” the concentration
gradient
Does NOT require
energy
http://highered.mcgrawhill.com/sites/0072495855/student
_view0/chapter2/animation__how_
diffusion_works.html
Diffusion

Factors effecting the rate of diffusion
1. temperature (as temp increases rate
increases)
2. pressure (as pressure increases rate
increases)
3. steepness of the concentration
gradient (the steeper the gradient the
faster the diffusion)
Osmosis

Movement of WATER across a cell
membrane
Water always moves toward the higher
concentration of solute particles
Types of Solutions

Isotonic

Hypotonic

Hypertonic
Types of Solutions

Isotonic – solutes inside = solutes outside

Hypotonic – solutes are higher inside the cell



water flows in, cell swells
cell could burst if continues
Hypertonic – solutes are higher outside the
cell

water leaves cell, cell shrinks
Types of Solutions
Isotonic
Hypotonic
Water particle
Solute particle
Hypertonic
Types of Solutions
Effects on Animal Cells
http://www.nclar
k.net/osmosisPo
cus.gif
The pictures below are red blood cells in different concentrations
of salt solution. Identify which pictures are hypotonic, isotonic,
and hypertonic solutions.
Isotonic
Hypertonic
Hypotonic
Types of Solutions
Effects on Plant Cells
Which of these cells are in a hypotonic
solution? Hypertonic solution?
Hypotonic
Hypertonic
Onion cells plasmolysis
http://www.youtube.com/watch?v=SooSsKkJo1o
Types of Solutions
Effects on Plant Cells

Turgor pressurePlant cells fill with
water and press
against the cell
walls making the
cells rigid
Types of Solutions
Effects on Animal Cells


Contractile Vacuolesstructure in protists that
collects and expels
excess water out of the
cell to prevent the cell
from exploding (lysing)
http://www.youtube.com/watch?v=iG6D
d3COug4
Facilitated diffusion


Facilitated diffusion occurs when molecules
move from an area of high concentration to
an area of low concentration with the aid of
a protein molecule
Does not require
energy
http://highered.mcgrawhill.com/sites/0072495855/student_v
iew0/chapter2/animation__how_facili
tated_diffusion_works.html
Active Transport



Requires energy
moves from an area of low
concentration to an area of high
concentration
moves “up” or “against” the
concentration gradient
Active Transport
LOW
HIGH
ENERGY FROM ATP PUSHES MOLECULES ACROSS THE MEMBRANE
WATCH ACTIVE TRANSPORT
LOW TO HIGH ENERGY NEEDED
Active Transport
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animati
on__how_the_sodium_potassium_pump_works.html
Bulk Transport


Sometimes the size of the particle or
the amount that needs to be moved
through the membrane is too large.
Then bulk transport is used
Bulk Transport


Sometimes the size of the particle or
the amount that needs to be moved
through the membrane is too large.
Then Bulk transport is used
Bulk Transport


Endocytosis- movement into a cell by
forming a vacuole around the particles.
Exocytosis- movement out of a cell by
releasing the contents of a vacuole.
Bulk Transport
Endocytosis
Exocytosis
Bulk Transport


Pinocytosis- movement of large volumes of solution with
dissolved solutes in or out of the cell
Phagocytosis- movement of large particles into or out of
the cell
Bulk Transport


An amoeba feeds on a Paramecium
http://www.youtube.com/watch?v=W6rnhiMxtKU&fe
ature=player_embedded
Transport Video

http://www.youtube.com/watch?v=9wi
PhcKlhTw