Cell Transport

7-3Pgs. 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=moPJkCbKjBs

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