7.3 cell transport - woodbridge township school district 7-3...7.3 cell transport . cell...
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Lesson Overview 7.3 Cell Transport
Lesson Overview Cell Transport
Passive Transport
What is passive transport?
The movement of materials across the cell
membrane without using cellular energy.
• Examples: diffusion, facilitated diffusion and
osmosis.
Lesson Overview Cell Transport
Diffusion
The movement of
particles from an
area of high
concentration to an
area of lower
concentration.
http://www.youtube.com/watch?v=gXJMBg
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Lesson Overview Cell Transport
Diffusion
It stops when
the particles on
both sides are
evenly
distributed.
Lesson Overview Cell Transport Facilitated Diffusion
• The proteins in the cell membranes act as carriers, or channels, making it easy for certain molecules to cross.
• Facilitated diffusion: movement of molecules from an area of high concentration to an area of low concentration through special protein channels.
• No energy is required.
http://www.youtube.com/watc
h?v=LsTo73joO0U
Lesson Overview Cell Transport
Osmosis: An Example of Facilitated
Diffusion
• The water channel proteins in the cell are known as aquaporins.
• Aquaporins allow water to pass right through the cell membrane.
• Without aquaporins, water would diffuse in and out of cells very slowly.
• This movement of water is known as osmosis.
Lesson Overview Cell Transport
Osmosis: An Example of Facilitated
Diffusion
Osmosis is the
diffusion of water
from an area of
higher
concentration to
an area of lower
concentration
through a
selectively
permeable
membrane. http://www.youtube.com/watch?v=sdiJtDRJ
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Lesson Overview Cell Transport
How Osmosis Works
Isotonic: When the concentration is the same on both sides of the membrane.
Isotonicmeans “same strength.”
Ex. Cells bathed in fluids, such as blood, are in isotonic environments. These cells neither gain nor lose water.
Lesson Overview Cell Transport
How Osmosis Works
• Hypertonic When
the concentration of the
solution outside the cell
is stronger than the
concentration inside
the cell
• In a hypertonic
solution, water rushes
out of the cell, causing
animal cells to shrink
and plant cell vacuoles
to collapse.
Lesson Overview Cell Transport
How Osmosis Works
• Hypotonic When the concentration of the solution outside the cell is weaker than the concentration inside the cell.
• In animal cells: water rushes into the cell, causing it to burst (plasmolysis).
• In plant cells: it creates a pressure known as turgo pressure or osmotic pressure. http://www.youtube.com/watch?v=SSS3Et
KAzYc&feature=related
Lesson Overview Cell Transport
Osmotic Pressure
Force created as a result of the net movement of
water out of or into a cell.
Lesson Overview Cell Transport
Osmotic Pressure
Lesson Overview Cell Transport
Active Transport
• The movement of
materials against a
concentration
difference.
• requires energy.
http://www.youtube.com/watch?v=owEgqrq
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Lesson Overview Cell Transport
Active Transport
The active transport of
small molecules or
ions across a cell
membrane is generally
carried out by
transport proteins, or
protein “pumps,” that
are found in the
membrane itself.
Lesson Overview Cell Transport
Active Transport
– Larger molecules and
clumps of material can
also be actively
transported across the
cell membrane by
processes known as
endocytosis and
exocytosis.
Lesson Overview Cell Transport
Endocytosis
– process of taking
material into the cell by
means of infoldings, or
pockets, of the cell
membrane.
– The pocket that results
breaks loose from the
outer portion of the cell
membrane and forms a
vesicle or vacuole
within the cytoplasm.
Lesson Overview Cell Transport
Endocytosis
• Large molecules, clumps
of food, and even whole
cells can be taken up by
endocytosis.
• Two examples of
endocytosis are
phagocytosis and
pinocytosis.
Lesson Overview Cell Transport
Endocytosis
• In phagocytosis,
extensions of cytoplasm
surround a particle and
package it within a food
vacuole. The cell then
engulfs it.
• Amoebas use this method
for taking in food.
• Engulfing material in this
way requires a
considerable amount of
energy and, therefore, is a
form of active transport.
Lesson Overview Cell Transport
Endocytosis
• In pinocytosis, cells
take up liquid from the
surrounding
environment by
forming tiny pockets
along the cell
membrane.
• The pockets fill with
liquid and pinch off to
form vacuoles within
the cell.
Lesson Overview Cell Transport
Exocytosis
• Many cells also release
large amounts of material
from the cell, a process
known as exocytosis.
• During exocytosis, the
membrane of the vacuole
surrounding the material
fuses with the cell
membrane, forcing the
contents out of the cell.
Osmosis Worksheet Examples
Lesson Overview Cell Transport
90% H2O 10%
solute
85% H2O
15% solute
Type of Solution:
Lesson Overview Cell Transport
45% H2O 55%
solute
75% H2O
25% solute
Type of Solution:
Lesson Overview Cell Transport
90% H2O 10%
solute
90% H2O
10% solute
Type of Solution:
Lesson Overview Cell Transport
__% H2O 10%
solute
__% H2O
20% solute
Type of Solution: