Passive and Active Transport
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Transcript Passive and Active Transport
Outcomes:
• Identify the factors which
influence the rate and
direction of diffusion.
• Identify how osmosis is
related to diffusion and
the value of osmosis to
living organisms.
• Examine the
mechanisms of active
transport by identifying
and explaining the two
processes.
• Compare the similarities
and differences
between active and
passive transport.
**Don’t have to write these
out**
Passive and
Active
Transport
Unit 2- Cell Structure and
Function
Cellular Transport
Cellular
transport moves substances within
the cell and moves substances into and
out of the cell
There are 2 types:
1.
2.
Passive Transport
Active Transport
Passive Transport
These
types of transport do not require
energy
a)
b)
c)
Diffusion
Facilitated Diffusion
Osmosis
A) Diffusion
Remember
from years before that
particles in solids, liquids, and gasses are in
constant random motion (Particle Theory
of Matter)
Substances dissolved in water move
constantly in random motion
The random motion of these particles
creates DIFFUSION
The
amount of a substance in a certain
area is called CONCENTRATION
Substances diffuse from an area of higher
concentration to an area of lower
concentration
Watch the following video and draw the
diagram on the next page:
http://www.youtube.com/watch?v=Um6O
oN81rb4
Diagram of Diffusion
Diffusion
occurs until there is an equal
concentration of particles in an area/cell
The particles continue to move randomly,
but there is no overall change- this is
called DYNAMIC EQUILIBRIUM
Rate of Diffusion
3
main factors affect the rate that
diffusion occurs
1. Concentration
2.
Temperature
3.
When concentration is high, diffusion
happens quickly because there are more
particles to collide with each other
When temperature increases, the particles
collide more quickly
Pressure
When pressure increases, the particles
collide more quickly
B) Facilitated Diffusion
While
water can diffuse readily across a
plasma membrane, most other
substances need help
Happens through carrier and channel
proteins
The
CHANNEL PROTEINS in the plasma
membrane of the cell are used to diffuse
ions and small molecules across the cell
membrane (draw the diagram below)
http://kentsimmons.uwinnipeg.ca/cm1504/Image132.gif
CARRIER
PROTEINS are also used to move
substances across a cell membrane by
changing shape to help diffusion in a cell
(Draw the diagram)
http://www.biologyco
rner.com/resources/si
mpdiff.jpg
C) Osmosis
The
diffusion of water across a selectively
permeable membrane is OSMOSIS
Regulating the movement of water across
the plasma membrane is an important
factor in maintaining homeostasis
(draw the next diagram)
http://www.biologycorner.com/resources/osmosis.jpg
If
the concentration of solute is higher on
one side of the cell membrane, the water
will move towards the higher solute
concentration
This diffusion happens until dynamic
equilibrium occurs
Isotonic Solution
When
a cell is in a solution that has the
same concentration of water and solutes
is said to be in an ISOTONIC solution
Water moves into and out of the cell at
the same rate and cells keep their normal
shape
Hypotonic Solution
If
a cell is in a solution that has a lower
concentration of solute, the cell is said to
be in a HYPOTONIC solution
There is more water outside of the cell
than inside the cell which causes water to
move into the cell
The water moving into the cell creates
osmotic pressure
In
an animal cell, the water may enter the
cell so much so that it bursts
A plant cell will not burst if there is a high
osmotic pressure because the cell wall is
very rigid
Hypertonic Solution
When
the concentration of the solute
outside of the cell is higher than inside
Water moves outside the cell
Animal cells may shrivel because of water
loss
Plant cells wilt because the water vacuole
is empty
Draw the diagram:
http://4.bp.blogspot.com/yiAZAMJRq4s/Ta79K3vVk8I/AAAAAAAAACE/MhfD0z_ABi8/s1600/
hypo.jpg
Video Explanation
http://www.youtube.com/watch?v=AYN
wynwaALo
Active Transport
This happens when substances have to move
from an area of lower concentration to an
area of higher concentration
This process makes sure that cells have the
proper amount of substances inside of them
These forms of cellular transport REQUIRE the
use of ENERGY by the cell
a)
b)
Pumps (carrier proteins)
Endocytosis/Exocytosis
A) Pumps (Carrier Proteins)
Carrier
proteins can move substances
against a concentration gradient
Some pumps move one type of
substance in one direction across the
plasma membrane
Other pumps move two substances in
both directions across the plasma
membrane
Sodium Potassium Pump
This
is a common type of pump
moves 3 sodium ions out of the cell
moves 2 potassium ions into the cell
ATP (a form of energy) breaks down into
ADP to do this
Video demonstration
http://www.youtube.com/watch?v=Q73uJ
8WlY_E
http://4.bp.blogspot.com/_207DNIaLgc/TOaSu8u3q7I/AAAAAAAAAV4/9QLnFO82wQA/s1600/07_16Sodium
PotassiumPump.jpg
B) Endocytosis & Exocytosis
Particles
that are too large to travel
through the plasma membrane leave or
enter the cell differently
Endocytosis
ENDOCYTOSIS
is when a cell surrounds
something outside of the cell
The cell membrane pinches off and
leaves the substance inside the cell
The substance is now in a vesicle to travel
throughout the cell
Exocytosis
Is
when substances leave the cell by
vesicles joining the plasma membrane to
expel the substance
http://www.kscience.co.uk/as/module1/pictures/endoexo.jpg