Transport (November 2nd)

Functions of membrane proteins

Move material

adhesion/recognition of cells

receives environmental signals

Types of membrane proteins

Integral proteins

Peripheral proteins

Glycoproteins

Lipid-anchored protein

Integral Proteins

Contain one more more regions that are hydrophobic and others that are hydrophilic

Carbohydrates

Oligosaccharides are bound to proteins or lipids and function in cell-to-cell recognition

Cell membranes are….

semi-permeable

What are the two types of transport?

Active and Passive

Passive Transport

does not need direct energy

Diffusion: simple vs. facilitated

high to low concentration

Active transport

Requires energy

low to high concentration

Diffusion

the movement of material to create an equilibrium

Equilibrium

equal concentration on both sides of the lipid bilayer

lipid bilayer=

plasma membrane

Factors that affect diffusion rates:

Concentration

Mass of molecule

Temperature

Solubility

Surface area

Distance

Pressure

Simple Diffusion across all membranes

gases and small nonpolar/uncharged molecules that diffuse across the lipid bilayer, going from high to low until the equilibrium is reached and there is no net movement

Facilitated Passive Transport

movement of substances down the concentration gradient through transport membrane proteins

Channel and Carrier Proteins

Channel Proteins

Some are open and some are gated until a signal

Carrier Proteins

Specific to a single substance, once bound to substance it changes shape to carry to other side of membrane

Movement in either direction

Osmosis

Diffusion of water across a membrane

Always from high to low

Osmolarity

the total solute concentration of a solution (permeable and non-permeable solutes)

Tonicity

relative concentration of solutes in a solution outside a cell

Hypertonic, Isotonic, Hypotonic

Hypertonic extracellular fluid

water leaves a cell (shriveled)

Isotonic Extracellular Fluid

No net movement of water (cell stays normal)

Hypotonic Extracellular Fluid

Too much water enters the cell (lysing)

Active Transport

Movement against the gradient and requires energy

Primary and Secondary

Primary Active Transport

moves an ion or molecules up its concentration gradient using energy from ATP hydrolysis

Secondary Active Transport

uses an electrochemical gradient created by primary active transport to move a different substance against its concentration gradient. No ATP