Movement of material in and out of cell: The basics & Passive Transport:

*How does stuff move in and out of an animal cell?

Cell membrane

-Selectively permeable

- things can go in and out of cell dependent on pore size.

- this is done to maintain homeostasis or equilibrium.

Equilibrium: Molecules are distributed evenly through out area

*What does it mean to be concentrated(not constipated or concentration)

*What happens to a piece of cheese when you grate it?

*Does the cheese increase or decrease in concentration?

The movement from one place to another is separated by a concentration gradient

Concentration Gradient

-  a difference in concentration between two places but is gone when equilibrium is reached

-  example there is a gradient present in picture a but in b equilibrium has been reached thus not gradient

In picture b the molecules are still in movement but they are moving at the same rate(no net movement)

Picture A

Picture B

2 types of cellular transport

a. passive transport

b. active transport

*What dose passive mean? (Relation to energy)

- No use of energy.

A. Passive transport

-  no energy used by cell to move particles across membrane

-  potential energy

-energy not in use

-stored energy

Kinetic Energy – energy in motion

1.  Diffusion (example of passive transport)

  1. Movement of molecule from greater to lesser concentration until equilibrium is reached. *hint remember the air freshener in class J
  1. Example of Diffusion is Osmosis – the movement of water from high to low concentration.

B. Active Transport (3 types)

Requires the cell to do work – (2 reasons why energy is required)

A. The cell has to rid itself of excess material the just keeps flowing back into the cell ….kinda like water in a sinking ship.

B. Some times the molecules are too large to fit through the pores of the membrane.

3 Type of Active Transport

1.  Ion transport (ions are atoms with a change- they are small)

  1. A.K.A. Facilitated Diffusion

*Substances move against the concentration gradient – low -> concentration

2.  Endo-Cytosis (endocytosis)

“into Cell”

-Large molecules which are too big to go thru pores can be taken in this way – this takes energy!

-This is how a cell eats and drinks…..

3. Exo-cytosis (exocytosis)

“out of cell”

Proteins (like insulin) are secreted from cell this is also how the cell rids itself of waste.

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