CELL TRANSPORT

PASSIVE TRANSPORT

Simple diffusion is the passive net movement of particles(molecules,ions and atom) that occur from region of high concentration to region of lower concentration

Rate of diffusion depends on:

Size of particles

Surface area

Concentration gradient

Temperature

a)simple diffusion

Facilitated diffusion is the diffusion of some substances across cell membrane with the help channel protein or carrier protein.Its does not required energy.The substances cross the membrane going down the concentration gradient

two types of protein are responsible for facilitated diffusion:

carrier protein 

channel protein.

a)Channel protein (allows specific ions to pass through the protein pore)    
  b)Carrier protein (binds to specific molecules)             




Osmosis is the movement of water molecules from higher water potential to the lower water potential through a semi permeable membrane.Osmosis does not required energyWater potential is a measure of the tendency for water to move from one place to another



ACTIVE TRANSPORT

 Active transport is when cells transport ions or molecules across the cell membrane through an opposite direction against a concentration gradient.It requires energy

Cells or tissue that carry out active transport usually have:
numerous mitochondria
high concentration of ATP
high respiratory rate

example:Sodium-potassium pump