Simple (Passive) Diffusion

Describe the direction of transport relative to theconcentration gradient:

Molecules move down a concentration gradient. They movefrom region of higher concentration to one of lower concentrationbecause of random thermal agitation.

Describe where the energy for transport comes from:

No metabolic energy input is required.

Describe IF and HOW membrane proteins participate:

No membrane proteins are used for this transport.

Discuss whether or not this type of transport offers the cellspecificity. i.e., can the cell regulate what goes in andout?:

Does not regulate the cell specificity.

Facilitate Diffusion

Describe the direction of transport relative to theconcentration gradient:

Molecules move down a concentration gradient. They movefrom region of higher concentration to one of lowerconcentration.

Describe where the energy for transport comes from:

No metabolic energy input is required.

Describe IF and HOW membrane proteins participate:

Uses carrier molecules (permeases) by attachment.

Discuss whether or not this type of transport offers the cellspecificity. i.e., can the cell regulate what goes in andout?:

The membrane carrier can change conformation after binding onexternal molecule and subsequently release the molecule on the cellinterior.

Primary Active Transport

Describe the direction of transport relative to theconcentration gradient:

Movement of ions or molecules across a cellular membrane from alower to a higher concentration.

Describe where the energy for transport comes from:

ATP, sunlight, etc.

Describe IF and HOW membrane proteins participate:

Involves carrier proteins (permeases) by attachment.

Discuss whether or not this type of transport offers the cellspecificity. i.e., can the cell regulate what goes in andout?:

Concentrates molecules inside the cell.

Secondary Active Transport

Describe the direction of transport relative to theconcentration gradient:

Molecules move against the gradient. They move from low tohigh concentration.

Describe where the energy for transport comes from:

ATP, sunlight, etc.

Describe IF and HOW membrane proteins participate:

Attaches to a carrier protein.

Discuss whether or not this type of transport offers the cellspecificity. i.e., can the cell regulate what goes in andout?:

Concentrates molecules inside the cell.