Cell Transport Vocabulary

Solution – Solute - Solvent • Solute – The substance that dissolves to form

a solution

• Solvent – The substance in which a solute dissolves

• Solution – A mixture of one or more solutes dissolved in a solvent

Semi-permeable membrane

• This membrane lets certain molecules pass through and prevents others from crossing

Passive transport

• the movement of substances across the plasma membrane from areas of high concentration to low concentration; does not require cellular energy.

• EX: – Diffusion

– Facilitated diffusion

– Osmosis

Diffusion

• the movement of particles from areas of higher concentration to areas of lower concentration.

Facilitated Diffusion

• A process where a substance passes through a membrane with a aid of an protein carrier, no energy required Protein Carrier

Osmosis • diffusion of water through a semi-permeable

membrane

• Water will move in the direction where there is a high concentration of solute (and hence a lower concentration of water)

Osmotic Pressure

• The pressure exerted by the flow of water through a semipermeable membrane separating two solutions with different concentrations of solute.

• EX:

– Hypotonic solution

– Hypertonic solution

– Isotonic solution

Osmotic Solutions • Hypotonic solution (“POW”)

– If concentrations of dissolved solutes are less outside the cell than inside, the concentration of water outside is correspondingly greater.

• When a cell is exposed to such hypotonic conditions, there is net water movement into the cell causing cell to burst.

Osmotic Solutions

• Hypertonic solution – If concentrations of dissolved solutes are greater outside the cell, the concentration of water outside is correspondingly lower.

• As a result, water inside the cell will flow outwards to attain equilibrium, causing the cell to shrink.

Osmotic Solutions • Isotonic solution - When cells are in isotonic

solution, movement of water out of the cell is exactly balanced by movement of water into the cell.

Active transport • the movement of substances across the plasma

membrane from areas of Low concentration to high concentration; requires cellular energy.

• The movement of macromolecules(large molecules such as proteins or polysaccharides into or out of the cell is called bulk transport.

• 2 types of bulk transport

– Exocytosis

– Endocytosis

Active Transport

• Endocytosis - the process by which materials move into the cell.

• Phagocytosis - “cellular eating,” the cell’s plasma membrane surrounds a macromolecule

• Pinocytosis - “cellular drinking,” the cell engulfs drops of fluid by pinching in and forming vesicles

Active Transport

• Exocytosis - materials are exported out of the cell via secretory vesicles

– Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane.

Concentration Gradient

• a difference between concentrations in a space

Equilibrium

• a state of equilibrium is reached when the concentrations of solutes and water is the same inside and outside the cell.

Dialysis

• the process of solute movement across a semi-permeable membrane.