Transcript Cell Membrane Movement

Cell Membrane Movement
_____ tends to diffuse from an
area of ____ water concentration
to an area of _____ water
concentration.
Comparing solutions
• A __________ solution is a solution in
which the concentration of dissolved
substances is _________ than the
concentration inside the cell.
• If a cell is placed in a hypertonic solution,
osmosis will make the water _____ the cell
and the cell will shrink.
Comparing solutions
• A _______ solution is a solution in which
the concentration of dissolved substances
is _______ than the concentration inside
the cell.
• If a cell is placed in a hypotonic solution,
osmosis will cause water to move through
the plasma membrane _____ the cell and
the cell will burst.
Comparing solutions
• An ______ solution
is a solution in which
the concentration of
dissolved substances
is the _____ as the
concentration inside
the cell.
• Psst! Remember
“equilibrium”?
Osmotic Pressure
Osmosis exerts a pressure known as ________
_________ on the hypertonic side of a selectively
permeable membrane.
Osmotic Pressure
Because the cell is filled with salts, sugars,
proteins, and other molecules, it will almost
always be _________ to fresh _______.
• If so, the osmotic pressure should produce a net
_________ of water into the cell. As a result, the
volume of the cell will _________ until the cell
becomes swollen or bursts.
Osmosis
• Cells in _______ organisms are not in
danger of bursting because they are bathed
in fluids, such as blood, that are _______.
• Other cells are surrounded by tough cell
walls that prevent the cells from expanding
even under tremendous osmotic pressure.
Facilitated Diffusion
_____ ________
have protein
channels that act as
carriers, making it
easy for _______
molecules to cross.
Facilitated Diffusion
• The movement of specific molecules
across cell membranes through protein
channels is known as _______ _______.
• Hundreds of different protein channels
have been found that allow particular
__________ to cross different membranes.
Facilitated
Diffusion
Glucose
molecules
Protein
channel
Facilitated Diffusion
• Although _________ diffusion is fast and
specific, it is still diffusion.
• Therefore, facilitated diffusion will only
occur if there is a ______ concentration of
the particular molecules on one side of a cell
membrane as compared to the other side.
Active Transport
• Sometimes ______ move materials in the
________ direction from which the materials
would normally move—that is against a
concentration difference. This process is
known as ______ _______.
• Active transport requires energy.
Active Transport
Molecular Transport
* In active transport, _____ molecules and ions
are carried across membranes by proteins in the
membrane.
* Energy use in these systems enables cells to
_________ substances in a particular _______,
even when diffusion might move them in the
opposite direction.
Active Transport
• This
transports
particles
_______ a
concentration
difference.
• This forced
movement
requires
energy.
Molecule to be carried
Active Transport
Endocytosis and Exocytosis
– ______ molecules and even ______ clumps of
material may undergo active transport through the
____ ________.
– ____________ is the process of taking material
into the cell by means of infoldings, or pockets of
the cell membrane.
– The pocket breaks loose from the outer portion
of the cell membrane and forms a _______ within
the cytoplasm.
Two examples of endocytosis are
phagocytosis and pinocytosis.
• In __________, extensions of cytoplasm
surround a particle and package it within a
food vacuole. The cell then engulfs it.
• Phagocytosis requires a considerable
amount of ______.
Two examples of endocytosis are
phagocytosis and pinocytosis.
• In _________, tiny pockets form along the
cell membrane, fill with _______, and pinch
off to form vacuoles within the cell.
Active Transport
Exocytosis
– Many cells also release ______ amounts of
material from the cell, in a process called
________.
– During _________, the membrane of the
vacuole surrounding the material fuses with the
____ _______, forcing the contents out of the cell.
End of Membrane movement notes
Any questions?