Plasma Membrane and Transport

Solute Potential

Ys = -i c R T

the further from zero, the more likely the solute will diffuse

always negative

i =

ionization constant (1.0 for sugar)

C =

sugar molar concentration (moles per liter)

R =

pressure constant (0.0831 liter bar per mole Kelvin, the standard atmosphere pressure)

T =

temperature (Kelvin + 270)

Water Potential

Y = Yp + Ys

where Yp is pressure potential and Ys is solute potential

kidney filtration

nefrons are the functional units of the kidney responsible for filtering blood, reabsorbing substances, and forming urine.

kidney filtration: 1st Tube

water diffusing out of nephrons (not all of it), solutes are left over

kidney filtration: 2nd Tube

salt starts to diffuse out, will go to active transport at some point, remaining water is diluted and solutes are further concentrated.

kidney filtration: 3rd Tube

hydrated, ADH gets rid of water, to bladder, dehydrated, ADH sends signals to reclaim water, stays in kidneys, goes to bladder

saturated solution

contains the maximum amount of solute that can dissolve in a solvent

plasma membrane

regulates what enters and leaves the cell and also protects and supports the cell

endocytosis

is the process by which cells take in substances from their external environment like food and water, by engulfing them in a membrane.

exocytosis

is the process by which cells expel substances from within the cell to the external environment by vesicular transport.

the plasma membrane is made up of …

lipids (phospholipids) and proteins

phosphate head of the phospholipid

is the hydrophilic part that interacts with water and helps form the plasma membrane's structure.

lipid tails of the phospholipid

is the hydrophobic part that repels water and helps create a barrier in the plasma membrane

pheripheral proteins

are proteins located on the outer or inner surface of the lipid bilayer,  a plays roles in signaling and maintaining the cell's shape.

intergral proteins

span the membrane from one side to the other, and are free to move around in the membrane if they are trans membrane proteins

diffuse easily across membrane

small, nonpolar molecules like O2 and CO2 and along with some small, uncharged polar molecules such as ethanol and water

diffuse with difficulty across membrane

large molecules, polar molecules, and charged molecules (ions)

transmembrane protein

intergral proteins that are free to move around the membrane

transport proteins

act as channels or tunnels for hydrophilic substances, through which modules may pass

carrier proteins

transport proteins that change shape and bind to specific substances

aquaporins

transport, channel proteins that facilitate the passage of water

potasium sodium pump

active transport proteins, uses ATP hydrolysis to move 3 Sodium ions (Na +) out o the cell, and 2 Potassium ions (K+) into the cell eachcycle

polar

molecules that have distinct electrical charges, leading to uneven distribution of electron density.

nonpolar

Describes molecules that do not have distinct poles or charge distribution, typically soluble in fats and oils, but insoluble in water.

solute

the component that is dissolved

solvent

substance that dissolves the solute

solution

a homogeneous mixture formed when a solute dissolves in a solvent

turgid

cell is firm and swollen, supported by high internal water pressure against the cell wall, in hypotonic solution, helps plants stand upright

flaccid

cells are limp and soft, lacking interior pressure, due to water loss/low water content, in hypertonic solution

concentration gradient

the difference in concentration of a substance across a membrane/space, causing molecules to move from an area of high concentration to an area of low concentration

cholesterol

a lipid that maintains fluidity of the membrane by inserting itself between phospholipid molecules, preventing them from packing too lightly and provides structural support

ionic bonds

electrostatic attractions between oppositely charged ions that form when electrons are transferred between atoms

selective permeability

allowing some substances to cross more easily than others, to protect the cell and maintain homeostasis