Cellular Transport
Membrane Structure consists of
1. Cell membranes are composed of a
double- layered sheet called a ___
2. Membrane Proteins
• Proteins run through the lipid
bilayer and form ___________
and ___________ to move
material across the cell
membrane.
3. Carbohydrate Molecules
• Polysaccharide chains attach
to the __________surfaces of
proteins.
• Many carbohydrates act like
chemical ____________ cards,
allowing cells to identify one
another.
What does a Cell Membrane DO?
• The cell membrane ___________
what enters and leaves the cell.
• The cell membrane provides
protection and support.
• The cell membrane helps to take in
food, water and ions and eliminates
wastes.
–Some molecules, like water moves
freely through the membrane, other
molecules must be carried/pumped
through channels.
Passive Transport – ___________ of
molecules across a cell membrane
that does NOT use energy
Molecules move ___________ a
concentration gradient from high
concentration to low
concentration
Three types of passive
transport…
Concentration Gradient
• A ___________ in number of molecules (or
ions) of a substance between two adjacent
regions.
Equilibrium
• After the substances move from
high to low concentration, then the
concentration of the substance on
both sides of the membrane will be
the same (___________ ).
–Even after equilibrium is reached,
individual molecules ___________ to
move rapidly across the membrane in
both directions.
Types of Passive Transport
• Diffusion is the ___________
of molecules from high
concentration to low
concentration.
–process by which substances
spread through a liquid or gas.
• NO ___________ required
• Substances such as _________ uncharged
polar molecules and small lipids easily
diffuse across the phospholipid bilayer.
Types of Passive Transport
• Osmosis – the diffusion of ___________
through a selectively permeable membrane.
(water molecules move from high to low
concentrations)
– Since water molecules are small, they can slip through
the gaps between phospholipids in the cell membrane.
– As a result, water molecules constantly move back and
forth through the cell membrane.
• Permeable- if a substance is
___________ to diffuse across a
membrane
• Impermeable- if things ___________
pass across the membrane
• Selectively Permeable –some
substances can pass across, others
cannot.
• Example-Osmosis
• Example shows a membrane
that is permeable to water
but is not permeable to
sugar.
• On one side of membrane is
a sugar solution, other side
is pure water.
• As a result, there is a net
movement of water into the
sugar solution. This is due to
diffusion (movement from
high concentration to
regions of low
concentration).
Types of Passive Transport
• Facilitated Diffusion- uses carrier
___________ to shuttle molecules across the
lipid bilayer without energy. (high to low
conc.)
ex: transports large ___________
molecules from the blood into body cells.
Why do water molecules move with osmosis?
• Osmoregulation- the control of ___________
movement across the cell membrane.
– Water “follows” solute.
• Solute- a substance ___________ in solvent
• Tonic- term used to refer to solvent
– Hypertonic- more solute in solvent outside of cell
– Hypotonic- less solute in solvent outside of the cell
– Isotonic- equal amount of solute outside of cell and
inside of cell.
• Solute is usually charged and does not move through
membrane
Why do water molecules move with osmosis?
• Hypertonic solution
– Solute concentration outside
the cell is HIGHER than solute
concentration inside the cell.
– Net movement of water
___________ the cell to
follow solute
• Cell shrinks
– Plasmolysis– Crenation-
Why do water molecules move with osmosis?
• Hypotonic solution
– Solute concentration outside
the cell is LOWER than solute
concentration inside the cell.
– Net movement of water
___________ the cell to
follow solute
• Animal cell swells and will
possibly burst
– ___________
• Plant cell swells until cell walls
restrict further swelling
– ___________ pressure
Why do water molecules move with osmosis?
• Isotonic solution
– Solute concentration is
the ___________ inside
and outside the cell.
– Water moves equally
into and out of the cell.
No net movement of
water
• Normal Cell structure
and function.
Active Transport – uses ___________ to move
substances across a cell membrane.
the movement of molecules and ions ___________
the concentration gradient.
(Low to High concentration)
Example of Active Transport
• Sodium-potassium pump- uses ATP (cell energy)
to push Sodium outside of the cell and Potassium
into the cell. These concentration gradients of
sodium and potassium allow for cellular
communication.
Types of Active Transport
• Bulk Movement (___________
molecules)- Transporting very large
molecules such as polysaccharides or
large proteins across the membrane.
• Materials all move across the cell
membrane packaged in membranebound sacs called ___________ . The
vesicle merges with the cell membrane.
Types of Active Transport
• Endocytosis- materials are
brought ___________ the
cell.
 a portion of the cell
membrane surrounds
desirable macromolecules
that are outside the cell. The
cell pinches off and the new
vesicle moves into the cell.
Example: when white blood
cells engulf foreign particles
like bacteria and viruses.
Types of Endocytosis
• Pinocytosis- ___________ transported into cell
• Phagocytosis- ___________ particles transported
into cell
• http://www.youtube.com/watch?v=pvOz4V699gk
Types of Active Transport
• Exocytosis- materials
___________ the cell
• wastes and cell
products are
packaged by the
Golgi Apparatus in
sacs called vesicles.
They then fuse with
the cell membrane
and the materials in
the vesicles are
secreted out of cell.
• Ex: tear production
In Da Club- best review video 
https://www.youtube.com/watch?v=dPKv
HrD1eS4