Lecture 2: Cell Membrane And Membrane Transport Flashcards
2 properties of particles that influence their permeability
-solubility of particle in lipid (charge)
-size of particle
4 types of passive transport
-diffusion
-osmosis
-channel mediated
-facilitated diffusion
diffusion aka
simple diffusion
simple diffusion
movement of solutes across lipid bilayer from high to low concentration
osmosis
diffusion of water across membrane
channel mediated transport
diffusion through a protein channel (ion channel)
facilitated diffusion
carrier mediated diffusion
2 types of active transport
-primary
-secondary
both types of active transport involve
moving solutes against concentration gradient, requiring energy
diffusion depends on what
brownian motion - random thermal motion of molecules
what is fick’s law of diffusion: general
-various factors affect diffusion rate
-net rate of diffusion is proportional to concentration gradient
what are the factors that affect diffusion rate (5)
-concentration gradient
-surface area of membrane
-lipid solubility
-molecular weight of substance
-distance (thickness) of membrane
which factors increase net diffusion rate (3)
-concentration gradient
-surface area of membrane
-lipid solubility
which factors decrease net diffusion rate
-molecular weight of substance
-distance/thickness
channel mediated transport: gated ion channel
-open in response to stimulus
-allow many ions in at once
-specific to ion
the sodium potassium pump is an example of what kind of transport
primary active transport
primary vs secondary active transport
-primary: ATP binds to the transporter
-secondary: ATP not directly used
what kind of transport is glucose transport
secondary
difference between carrier mediated transport and simple diffusion: transport rate v concentration
-transport maximum exists for carrier mediated transport as carriers will become occupied
-simple diffusion is linear, no limit
how does water move during osmosis
to area of higher solute concentration
higher solute concentration = _________ concentration of water
lower
what kind of transport protein is used in the movement of water
aquaporins
semi permeable membrane
-membrane is permeable to water but impermeable to solute
-only water moves
-causes increase in volume
-hydrostatic pressure and osmotic pressure are in equilibrium
osmolarity/osmolality definition
total concentration of particles per amount of solution
is osmolarity of intracellular and extracellular fluids the same or different
same
what happens if there is a higher concentration of an impermeable substance inside the cell
water is forced to move and cell volume and shape change
tonicity
ultimate effect a solution has on cell volume which determines whether cell size remains the same, swells or shrinks when a solution surrounds the cell
effective osmolarity
-osmolarity of non permeable particles in solution
-control actual movement of water
Osmolarity vs osmolality
-osmolarity is a volume measure
-osmolality is a mass measure
