The Cast of Chemicals

water

key ingredient in intracellular and extracellular fluid, polar solvent

ions

atoms are molecules with a net electrical charge, hydrophilic

phospholipid bilayer

Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside.

lipids: hydrophobic

phosphate groups: hydrophilic

lipids vs. phosphate groups

Proteins

molecules assembled from amino acids:

- enzymes

- cytoskeletal elements

- receptors

- ion channels

Transmembrane proteins

Integral proteins that span the membrane:

- control resting membrane potential & action potential

- control synaptic transmission

- control extracellular to intracellular signaling

Protein Structure

amino acids linked together via peptide bonds to form peptide bonds to form polypeptides

primary, secondary, tertiary, quaternary

4 levels of protein structure

Protein Structure: primary

sequence of amino acids

Protein Structure: secondary

coiling of polypeptide into alpha helix

Protein Structure: tertiary

3D folding of the polypeptide

Protein Structure: Quaternary

different polypeptides bonding together

1. charge separation: the neuronal membrane
2. selective permeability: ion channel proteins
3. concentration gradients: ion pumps (ex. Na+/K+ ATPase)

How is the resting membrane potential established and maintained?

-65 mV

what is the typical neuron at resting membrane potential?

electrical potential

the force exerted on a charged particle (ion)

Membrane potential

difference in electrical charge across the membrane, at rest the membrane has a steady negative electrical potential