Introducing Cell Transport

Cell Transport

Concentration Gradient Concentration Gradient ConcentrationConcentration – The amount of solute in a – The amount of solute in a

solutionsolution GradientGradient – A measure of how much – A measure of how much

something changes when you move from one something changes when you move from one region to another.region to another.

Put ‘em together and what do you get?Put ‘em together and what do you get? Concentration GradientConcentration Gradient - measurement of - measurement of

how the concentration of something changes how the concentration of something changes from one place to another.from one place to another.

Passive Transport

Passive TransportPassive Transport – Molecules moving from – Molecules moving from an area of high concentration to low an area of high concentration to low concentration.concentration. No energy needed No energy needed

Diffusion

The process by which molecules spread from The process by which molecules spread from areas of high concentration, to areas of low areas of high concentration, to areas of low concentration.concentration. Equilibrium – Concentration is equal Equilibrium – Concentration is equal

throughout solution. throughout solution.

Diffusion Animation

Osmosis

The movement of water molecules from high concentration to low concentration

Osmosis

Hypertonic: Water diffuses out of cell (Cell Shrinks)

Hypotonic: Water diffuses into cell (Cell swells)

Isotonic: Equal rate of water diffusion into and out of the cell (Cell Stays the Same)

http://staff.jccc.net/aalarabi/memb_related_mov.htm

Facilitated Diffusion

A form of diffusion facilitated by transport Proteins also known as carrier proteins

Facilitated Diffusion

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

Active Transport

Active Transport: The Transport of a substance across the cell membrane against its gradient

Requires Energy ( usually ATP)

http://staff.jccc.net/aalarabi/memb_related_mov.htm

Sodium/Potassium Pump

Bulk Transport

Endocytosis- The movement of a substance into a cell by a vesicle

Cell membrane forms pouch around substance and then pinches off

Bulk Transport

Exocytosis- The movement of substance by a vesicle to the outside of a cell

Vesicles fuse with cell membrane

Cells Must Be Small

All substances that enter or leave the cell must cross that cell’s surface

Small cells can exchange substances better than large cells

They don’t have to travel as far to reach the center

Cell Size: Surface Area To volume