Membrane transport

Membrane is permeable to substance.

Membrane is impermeable to substance.

Solubility is based on polarity, a molecule will be soluble in water if it is charged and polar, a molecule will not be soluble in water if it is uncharged and nonpolar.

If something is considered soluble then it wont be able to cross and will be blocked by nonpolar barriers. Not permeable.

Facillitated/Assisted Diffusion
Passive/Simple Diffusion
Vesicular

Endocytosis and Exocytosis. Will fuse with cell and transport nutrients inside.

When molecules can penetrate the membrane on their own

Increases molecule temperature, moving high to low concentration.

Increase:
- Concentration gradient
- Permeability of the plasma membrane to a substance
- Surface area of the membrane
Decrease:
- Molecular weight of a substance
- Distance

Carrier and Channel proteins

Form open fluid filled passageways, water and ion channels.
Used exclusively in facillitated diffusion.

Open channels are leaky channels or open water pores.
Gated channels are chemically gated, voltage-gated, and mechanically gated (stretching).

Physical interaction, changes conformation to move molecules.

Antiport - 2 molecules different direction in membrane
Symport - 2 molecules in the same direction in membrane.

Both require a helper.
Facillitated diffusion involves both channel and carrier proteins, down the gradient.
Active transport carrier proteins only, requires energy source, against the gradient.

Sodium (Na+) is being pumped out of the cell against the gradient. Potassium (K+) is being pumped into the cell against the gradient.