Unit 1 - Membrane Transport

2 categories for membrane transport

Passive transport and active transport.

passive transport

The movement of substances across a cell membrane without the need for energy, typically down their concentration gradient. Moves downhill

Active Transport

The movement of substances across a cell membrane that requires energy, typically against their concentration gradient. Moves uphill.

Plasma Membrane Phospholipid bilayer

Hydrophilic heads and hydrophobic tails

passive transport - 3 types

simple diffusion, carrier - mediated proteins (facilitated diffusion), and osmosis.

simple diffusion

material moving from area of high concentration to area of low concentration

carrier - mediated proteins

facilitated diffusion; material binds to membrane shuttling material through

osmosis

movement of water from area of low solute concentration to area of high concentration

characteristics of carrier mediated proteins

specifity, affinity, saturation, competition

osmosis - tonicity

if water moves and it affects the shape of the cell

osmosis - osmotic

if water moves and it affects the pressure of system

isotonic

no change in shape; solution of environment matches that of cell

isosmotic

no change in pressure of cell or environment

hypertonic

cell place in solution that concentration is higher than cell; water leaves causing it to shrink

hyperosmotic

pressure cell decrease, pressure in environment increases

hypotonic

cell placed in solution that has lower concentration than that of cell; water moves in causing cell to swell or burst

hyposmotic

pressure of cell increases and pressure of emvironments decreases

primary active transport

use of ATP to move materials

secondary active transport

movement of material is used with energy from another protein

endocytosis

movement of material into or internally of a cell

receptor mediated endocytosis

1. 1. binding

2. 2. vesicle formation

3. 3. uncoating

4. 4. fusion with endosome

5. 5. recycling of proteins

6. 6. digest LDLs

pinocytosis

endocytosis involving moving of liquid materials

phagocytosis

endocytosis involving moving of physical or solid material

exocytosis

movement of material out of or external to celltra

transcytosis

substance transported across the cell by being taken in on one side and released on the other side