Transcript Cell Transport - HRSBSTAFF Home Page

Cellular Transport
Biology 11
Cell Membrane

Selectively permeable


Allows some molecules to pass through while
stopping others
Continually allows water, gases, nutrients
and wastes to pass
What if the cell membrane was … ?

Permeable


Allowing all molecules to pass through
Impermeable

Allowing no molecules to pass through
Particle Theory

Molecules constantly move
in all directions

Bounce off of one another
when they collide

Result:

Molecules concentrated in one area spread
outward
Terms to Know

Solute



Solvent



Solid substance
E.g. sugar
Fluid
E.g. water
Solution

Solute + solvent mixed together
Concentration Gradient

Concentration of solutes is unequal on
either side of the membrane

Outside and inside of cell

Unequal distribution
Dynamic Equilibrium
A balance is reached and maintained
 Molecules continue to cross membrane


Rate of molecules entering cell will equal that
of them leaving
Passive Transport

Movement of materials across a cell
membrane without expending energy

Molecules move from high to low
concentration


With the concentration gradient
Until dynamic equilibrium
is reached
Types of Passive Transport
1.
Diffusion
2.
Osmosis
3.
Facilitated Diffusion

Flowing downhill
Passive Transport – Diffusion

When there is an unequal concentration of
gas or liquid molecules
Passive Transport – Osmosis

Diffusion of water

Membrane is permeable to water, but
impermeable to larger molecules

Cell may gain
or lose water
Osmosis – Water Movement

A solution that has the
same concentration of
solutes as the cell.

Therefore there is no
net movement of
water molecules
Hypertonic

The solution has
higher concentration
of solutes then the
cell.

Therefore there will be
a net movement OUT
of the cell.
Hypotonic

A solution that has a
lower concentration of
solutes than the cell.

There will be a net
movement of water
into the cell.
Passive Transport –
Facilitated Diffusion

When integral/carrier proteins in the
cell membrane aid diffusion

Materials move in and out of the cell much
more quickly than regular diffusion
Passive Transport –
Facilitated Diffusion
Passive Transport – Diagrams
Active Transport

Materials move from area of low to high
concentration



Requires energy


Against the concentration gradient
Makes concentration gradient more unequal
ATP – adenosine triphosphate
Integral/carrier proteins
may be used
Active Transport – Diagram
Other Types of Active Transport

1.
2.
Endocytosis
a.
Pinocytosis
b.
Phagocytosis
Pushing
something uphill
Exocytosis
No proteins used with these!
Animation
Active Transport – Endocytosis

Movement of large particles into the cell

Extends cytoplasm around it to engulf
(completely surround) the particle
Types of Endocytosis

Phagocytosis


Pinocytosis

Liquid droplets are
engulfed
Large molecules, or
even whole cells,
are engulfed

Solids
Active Transport
Active Transport – Exocytosis

Movement of large particles out of the cell

Vesicles fuse to cell membrane


Dump interior of vesicle outside of cell
Often eliminates
wastes
Active Transport – Exocytosis
Active Transport – Diagrams
Task

Read:



Pages 50-53 & 56-57
Summary: pages 57-58
Answer:

Practice Questions:
#1, 2a, 3 – 6 (pg 57)
#1 – Affects Diffusion Rates:

Concentration



Pressure


Difference between inside and outside of cell
Larger difference = faster
High pressure = faster
Temperature


Which is faster?
High temperature
Did you know?

Average cell is 20–30 µm
 3 seconds for oxygen to enter @ room
temperature

If it was 20 cm …
 it would take
11 years!
#2(a) - Solutions

Isotonic


Hypotonic


Concentration of solutes outside cell is
equal to that inside
Concentration of solutes outside cell is
less than inside
Hypertonic

Concentration of solutes outside cell is
greater than inside
#3 – Diffusion Compared
Facilitated Diffusion


Carrier/integral
protein used
Diffusion/Osmosis

Proteins not used

Quicker movement

Movement
through
phospholipids
Slower
movement
#4 – Passive vs. Active Transport
Passive
Active

No energy used

Energy used

Movement WITH
concentration
gradient

Movement AGAINST
concentration
gradient


From high to low
concentration
(Flowing downhill)


From low to high
concentration
(Pushing uphill)
#5 – Endocytosis

Pinocytosis



Phagocytosis


Intakes or engulfs small liquid droplets
E.g. water and fats
Intakes or engulfs solid particles
Both use energy!
#6 – Endo vs. Exocytosis
Endocytosis

Molecules entering
cell
Exocytosis

Molecules exiting
cell (removed)



Cytoplasm
extended around
molecule
Both use energy

Move to external
environment
Fuses with
cytoplasm
Extra Questions
1.
How are osmosis and diffusion alike?
How are they different?
2.
Someone sprayed perfume at the front of
the classroom. You smell it at the back
of the room a short time later. Explain
what has occurred.
Task: Complete Review Chart
Passive Transport
Diffusion
Requires energy
Requires integral
proteins
Moves from ? to
?concentration
Movement across
concentration
gradient
Moves what
materials
Osmosis
Facilitated
Diffusion
Active
Transport
Task: Complete Review Chart
Passive Transport
Diffusion
Requires energy
Requires integral
proteins
Moves from ? to
?concentration
Movement across
concentration
gradient
Moves what
materials
Osmosis
No
Facilitated
Diffusion
Active
Transport
Yes
Task: Complete Review Chart
Passive Transport
Diffusion
Requires energy
Requires integral
proteins
Moves from ? to
?concentration
Movement across
concentration
gradient
Moves what
materials
Osmosis
Facilitated
Diffusion
No
No
No
Active
Transport
Yes
Yes
Usually
Task: Complete Review Chart
Passive Transport
Diffusion
Requires energy
Requires integral
proteins
Moves from ? to
?concentration
Movement across
concentration
gradient
Moves what
materials
Osmosis
Facilitated
Diffusion
No
No
No
High to Low
Active
Transport
Yes
Yes
Usually
Low to High
Task: Complete Review Chart
Passive Transport
Diffusion
Requires energy
Requires integral
proteins
Osmosis
Facilitated
Diffusion
No
No
No
Active
Transport
Yes
Yes
Usually
Moves from ? to
?concentration
High to Low
Low to High
Movement across
concentration
gradient
With
Against
Moves what
materials
Task: Complete Review Chart
Passive Transport
Diffusion
Requires energy
Requires integral
proteins
Osmosis
Facilitated
Diffusion
No
No
No
Active
Transport
Yes
Yes
Usually
Moves from ? to
?concentration
High to Low
Low to High
Movement across
concentration
gradient
With
Against
Moves what
materials
Liquids &
Gases
Water
Solids
(& gas)
Solids
What is the end result?

Passive transport


Reaches dynamic equilibrium
Active transport

Makes molecules more unequal
Videos

Aliant Learning
 Cell Movement and Transport 2001 - 15 min

http://www.youtube.com/watch?v=GW0lqf4Fqpg

http://www.youtube.com/watch?v=JShwXBWGM
yY

MacGraw Hill Animations
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapte
r2/
