Download Cell Transport

Cell Transport
7-3
Pgs. 182-189
Cell Membrane
• Cell membrane regulates what leaves and
enters the cell.
• It is a lipid bilayer with proteins embedded
in the layer.
Phospholipids
• Phosphate head- polar “likes” water
• Lipid tail- 2 fatty acids- non-polar- does not
“like” water
Phospolipid Bilayer
• There are 2 types of proteins in the lipid
bilayer
– Integral Proteins- transport substances across
membrane
– Peripheral Proteins- bind to the bilayer
temporarily, perform various cellular
processes.
Phospholipid Bilayer
• Cholesterol plays an important role in
maintaining the integrity of the membrane.
– Keeps it firm and from becoming too
permeable.
• Carbohydrates- Act as cell markers, allow
cells to identify each other.
Cell Membrane Video
• http://www.youtube.com/watch?v=moPJk
CbKjBs
Diffusion
• All cells must exist in a liquid environment
in order to survive.
• A solution is a mixture of two or more
substances.
• Solute- substance dissolved into the
solvent
• Solvent- substance solute dissolves into.
– Ex- iced tea mix is the solute, water is the
solvent
Diffusion
• Particles are constantly moving in a
solution.
• Particles tend to move from an area of
high concentration to an area of low
concentration, this is called diffusion.
• Movement from high to low concentration
is called the concentration gradient
Diffusion
Equilibrium
• Particles move from high to low conc. until
they are the same throughout the system,
this is called equilibrium
Diffusion
• Since particle movement is random,
diffusion occurs across the membrane
without the use of energy.
– Called Passive Diffusion
Osmosis
• Osmosis is the diffusion of water across a
selectively permeable membrane.
Osmosis
• Water will move across a membrane until
the concentrations of water and the solute
are equal, this is an isotonic solution.
• Hypertonic solution- when there is more
solute then water. concentrated
• Hypotonic solution- when there is more
water then solute. dilute
Facilitated Diffusion
• Proteins in the cell membrane allow some
substances pass through easier then
others.
• Still follows concentration gradient
• Ex- doorman at a club, lets some people in
easier then others
Active Transport
• Sometimes particles have to move from
low to high concentration, against the
concentration gradient.
• This requires energy and is called active
transport.
• Ex- swimming against the current of a
river.
• Use proteins to carry particles across
Endocytosis and Exocytosis
• Particles that are too large to pass through
the membrane other ways
• Endocytosis- the cell membrane folds
around an object and envelops it.
Endocytosis and exocytosis
• 2 types of endocytosis
–Phagocytosis- used for taking in
food particles
–Pinocytosis- used for taking in
liquids
Exocytosis
• Exocytosis is a process used to release
substances from the cell.
• Vacuole fuses with the cell membrane and
forces contents out of cell