Midterm 3 Flashcards
cell membranes
selective barriers for receiving info, motility, molec import/export
arrangement of ambiphatic lipids and proteins in a biological membrane
lipid bilayer of phospholipids with hydrophilic heads and hydrophobic tails
water forms a cage-like structure around
hydrophobic molecs
hydrophilic molecs
form bonds with w
phospholipids form what in water
liposome
bilayer and flip-flop
lipids can move laterally but rarely flip flop
2 properties that affect membrane fluidity
- length of carbon bond (shorter = more fluid, longer = less fluid)
- # of double bonds (unsaturated has double bond = more fluid, saturated has none = less fluid)
proteins can be associated with the membrane by
asymmetric distribution of phospholipids is caused by
scramblases and flippases
proteins fabricated in the non-cytosolic/lumen will be transported to
the plasma membrane (extracellular space)
cytosolic facing proteins
remain cytosolic
membrane domains are formed
by tethering proteins to structures inside/outside the cell
glycocalyx
carbohydrate layer on plasma membrane
functions of sugars in glycocalyx
protects the cell from mechanical damage and functions in cell-cell recognition and adhesion
what major ions are in high concentration inside cells
K+, Na+, Cl-
which molecs will diffuse fastest across a lipid membrane
smaller, hydrophobic
simple diffusion
molecs move from one location to another by random, thermally driven motion
passive transport
spontaneous movement of a solute down its electrochem grad
active transport
movement of a solute across its electrochem grad (uses E)
ion channels
allows ions through a channel based on size/electric charge
ion transporters
transport ions/molecs that fit into specific binding site
concentration gradients and electrochem forces drive passive transport via
electrochem grad
3 mechanisms for moving solutes against their electrochem grads
- coupled pumps
- ATP-driven pumps
- light-driven pumps
Na/K pump
Na+ out, 2K+ in - uses ATP; high Na+ outside high K+ inside
Ca2+ pump
pumps out of the cell using ATP (cell comm. and muscle contraction)
Na+ and glucose transporter on gut cells
uses import of Na+ to import glucose
what electrochem grad is used to import/export solutes in plants/bacteria/fungi
electrochem H+ grad
ion channel selectivity
only those with appropriate size and charge will pass
voltage-gated ion channels
controlled by membrane potential
ligand-gated ion channels
opening controlled by binding of the ligand
mechanically-gated ion channels
controlled by mechanical force
a trace from a patch clamp recording
shows current over time passing thru membrane channels
resting potential of the cell is established
differences in voltage across plasma membrane
action potential
traveling wave of electrical excitation used to carry messages by neurons
how do neurons transmit signals across synapses
triggered by the entry of Ca2+ in the postsynaptic cell that can adjust the amount of neurotransmitter released, or adjust how the postsynaptic cell responds
drugs
blocks uptake or makes channels easier to open
optogenetics
uses light to control the neurons that have light-gated ion channels
