This document discusses different types of membrane transport mechanisms. It describes passive transport mechanisms like diffusion and facilitated diffusion which move molecules down concentration gradients without chemical energy. Active transport requires chemical energy from ATP and uses carrier proteins to move substances against gradients. Endocytosis and exocytosis also utilize vesicles and require ATP to move materials into and out of cells. Channel and carrier proteins are involved in both passive and active transport and determine which substances can pass through the membrane.

1. Chapter 2A

2.  Understand what is meant by passive
transport (diffusion, facilitated diffusion),
active transport (including the role of ATP as
an immediate source of energy), endocytosis
and exocytosis
 Understand the involvement of carrier and
channel proteins in membrane transport.

3.  Size of molecule
 Solubility of molecule
 Presence and absence
of charges
 Example : steroids pass
easier than sodium ion

4.  Occurs when there are concentration,
pressure or electrochemical gradients,
without chemical energy.

5.  3 main types:
 1. Diffusion – the movement of particles in a
liquid or gas down a concentration gradient.
 2. Facilitated diffusion – takes place through
carrier or channel proteins.
 3. Osmosis – movement of solvent molecules
down a water potential gradient by partially
permeable membrane.

7.  Movement of substances by the using of ATP.
 Uses always carrier protein.

8.  Uses vesicles for movement
 ATP is also important
 2 main types are:
 1. Endocytosis
 2. Exocytosis

10.  Important for ions, polar substances.
 Involves proteins(channel or carrier) in the
membrane that allow specific substances to
move passively down the gradient.
 Proteins are specific to molecule.