Download Cell Boundaries

Cell Boundaries
HONORS BIOLOGY
Cell Membranes
1. One of the most important functions
of a cell membrane is:
to regulate the movement of
molecules into and out of a cell
2. A cell membrane is said to be
Selectively Permeable
__________________________
• Which means only specific kinds of
molecules can get through the
membrane
• Another word for it is
Semipermeable
______________________
3. Selectively Permeable
 Cell membranes let some molecules enter a cell, but
prevents other molecules from getting in.
Can Enter
- Water
- Small Molecules (O2 & CO2)
- Non-polar lipids
Can Not Enter
- Macromolecules
- Ions (Na+,Cl-)
- Hydrophilic
molecules (glucose)
5. Concentration
 The concentration of a solution is:
The mass of the SOLUTE divided by the
volume of the SOLUTION
For example: 10g/1L
The more solute per volume equals a greater
concentration.
6. Diffusion
The movement of molecules
from an area of high
concentration to an area of
lower concentration
Example of Diffusion:
 Beaker of water. Add salt to the water.
 Will all of the water be salty or just the side of the
beaker that you dumped the salt into?
 When you add salt the salt will diffuse to all of the
water.
Example of Diffusion:
 The smell of popcorn after
it’s been popped.
 Does the smell of popcorn
stay where the popcorn was
popped? Why or why not?
Diffusion
http://highered.mcgrawhill.com/sites/0072495855/student_vi
ew0/chapter2/animation__how_diffus
ion_works.html
Osmosis
The diffusion of water. The
movement of water from a high
water concentration to a low
water concentration.
Osmosis
http://highered.mcgrawhill.com/sites/0072495855/student_vi
ew0/chapter2/animation__how_osmo
sis_works.html
Hypotonic
Solution has a lower solute concentration than
the cell
Water enters the cell, animal cells can expand
and possibly burst.
Isotonic
The concentration of the solutes is the
same inside and outside the cell
Hypertonic
Solution has a higher solute concentration
than the cell
Water leaves the cell, animal cells can shrink.
Facilitated Diffusion
The movement of specific
molecules across cell membranes
through protein channels.
Facilitated Diffusion
http://highered.mcgrawhill.com/sites/0072495855/student_vi
ew0/chapter2/animation__how_facilit
ated_diffusion_works.html
Active Transport
Energy requiring process that
moves material across a cell
membrane against a
concentration difference.
Active Transport
http://highered.mcgrawhill.com/sites/0072495855/student_vi
ew0/chapter2/animation__how_the_s
odium_potassium_pump_works.html
Overview
Endocytosis: Taking material in to the cell
through cell membrane pockets
Phagocytosis: Solids or large molecules
moved
Pinocytosis: Liquids moved
Exocytosis: Releasing material from the
cell