HONORS BIOLOGY

Cell Boundaries

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 __________________________• Which means only specific

kinds of molecules can get through the membrane

• Another word for it is ______________________Semipermeable

Selectively Permeable

3. Selectively Permeable

Cell membranes let some molecules enter a cell, but prevents other molecules from getting in.

Can Enter Can Not Enter- Water- Small Molecules (O2 & CO2)

- Non-polar lipids

- 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.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

Osmosis

The diffusion of water. The movement of water from a high water concentration to a low water concentration.

Osmosis

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

HypotonicSolution has a lower solute concentration than the

cellWater enters the cell, animal cells can expand and

possibly burst.

IsotonicThe concentration of the solutes is the same inside and outside the cell

HypertonicSolution has a higher solute concentration

than the cellWater leaves the cell, animal cells can shrink.

Facilitated Diffusion

The movement of specific molecules across cell membranes through protein channels.

Facilitated Diffusion

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_facilitated_diffusion_works.html

Active Transport

Energy requiring process that moves material across a cell membrane against a concentration difference.

Active Transport

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html

Overview

Endocytosis: Taking material in to the cell through cell membrane pocketsPhagocytosis: Solids or large molecules movedPinocytosis: Liquids moved

Exocytosis: Releasing material from the cell