Cell membrane physiology Flashcards
Exam 3
what is the plasma membrane
a boundary between intracellular fluid and extracellular fluid
what does the plasma membrane control
the contents of the cell
what passes into and out of the cell
what does the plasma membrane monitor
monitors the Extracellular fluid (ECF), like chemical signals and its composition
what does the plasma membrane do structurally
it provides structural support
how does the plasma membrane establish membrane potential
it seperates charges at rest- slighly more- on the inside
what are the 4 componenets in the plasma membrane
plospholipds
cholesterol
proteins
carbohydrates
What are the 3 components of phospholipds
glycerol
phosphate head
fatty acid tail
how much of the plasma membrane is phospholipids
75 %
what does glycerol do in phospholipds
it is a linking molecule
what does the phosphate head do in phospholipids
it is polar
water soluble/ hydrophilic
arranged that it faces toward both ECF and ICF
what does the fatty acid tail do in phospholipids
there are 2 per
non polar/ no charged regions
is water insoluble/ hydrophobic
what are two theories associated with phospholips
phospholipid bilyar and fuid mosaic model
what does the phospholipid bilayer do (info)
arranged in a way that minimizes hydrophilic/hydrophobic interactions
heads go to ETC and ITC, whereas the tails are sandwiched in the middle
What does the fluid mosaic model do (info)
it means that phopholipds can move freely within the membrane BUT they cant flip.
some of the molecules movements are limited
how much of the plasma membrane is cholesterol
25 %
what does cholesterol do
fill gaps between fatty acid tails
what happens when the plasma membrane is punctured
it can self seal. the vessicles do blebbing/fusing
what are the 2 things that cholesterol decreases
permeability to water and
fluidity
how does cholesteral decrease the cells permeability to water
it decreases space so that water can not sneak through. more cholesterol means less spaces for water to be sneaky through
how deos cholesteral decrease the cells fuidity
with the fluid mosaic model that a tighter fit means there will be less movement of phospholipids within the membrane
membrane proteins structure . what are the 2 types
integral are embedded within the whole membrane
peripheral are attached to either inside or outside of the membrane
what are some functions of membrane proteins
anchoring to the cytoskeleton
transport proteins
receptors
enzymes
recognition proteins
what are major histocompatibilaty complex proteins (MHC)
identify self vs. nonself or disease vs non disease cells.
This is huge for transplants and finding good matches
what is the main description for cell permeability
they are semi/selectively permeable
what does selectively permeable mean
that the cell regulates what enters and exits cell
this restriction is based on size, electrical charge, molecular shape, and lipid solubility
how is the movement across the membrane monitored / what is the order of molecules permeability scale (4)
High permeability
Small, nonpolar molecules
Small, uncharged polar molecules
Large, uncharged polar molecules
Ions
Low permeability
why are cells typically very small?
because they are limited by
how quickly stuff can enter or exit through the cell membrane and
how quickly stuff can move around in the cytoplasm
What is cell size limited by
surface area
as a cell size increase, what else increases
surface area and volume
what ratio is key to a cell
SA to Volume ratio
what does an increase in volume do to a cell
there is an increase in metabolism and an increase in the distance needed to travel within the cytoplasm
what 2 main things are cell size limited by
surface area and by the rate materials can cross the membrane
what are the two main types of transport
passive transport and active transport
what is passive transport
molecules move down a concentration gradient
no energy is needed
what is active transport
molecules move against a concentration gradient
energy is required
what are the 3 types of passive transport
diffusion, osmosis, and facillitated diffusion
what are the 2 types of active transport
active transport and vesicular transport
Diffusion process
particles go down concentration gradient .
move from high conc to low conc due to thermal energy
no energy is consumed
osmosis process
diffusion of water across membrane
facilitated diffusion process
diffusion across membrane that is carrier mediated
what type of protein mediates facilitated diffusion
integral protein
what is diffusion def
random movement (of each molecule) of a substance from high to low concentration (net movement)
brownian movement def
molecules are in constant motion due to thermal energy
solute def
anything that is dissolved into a solution (like salt)
solvent def
what it is dissolved into (like water)
what is the rate of diffusion related to
temperature, concentration gradient, steepness, molecular size, electrical gradient, pressure gradient
why do living organisms consume energy
to advoid equilibrium
equilibrium def (in regard to diffusion)
the net movement in = the net movement out
tonicity def
related to solute concentration of 2 fluids
it predicts movement of water
osmotic pressure def
pulling pressure due to non diffusible solutes
isotonic solution def
same solute concentration in both solutions
hypertonic solution def
higher solute concentration and a lower water concentration
hypotonic solution def
low solute concentration and a higher water concentration
what is the rule of hyper and hypo tonic solutions
Water tends to move from (net) hypotonic solution to hypertonic solution (still random)
hydrostatic pressure def
pushing pressure due to volume of fluid
Equilibrium def (in regards to osmosis)
when osmotic pressure is equal and opposite to hydrostatic pressure
Two types of tonicity are
crenation and hemolysis
could you recover from crenation or hemolysis
crenation, yes
hemolysis, no
does hyper of hypo tonic cause crenation
hypertonic
does hyper or hypo tonic cause hemolysis
hypotonic
is facilitated or simple diffusion faster
facilitated
why is facilitated diffusion faster
membrane itself limits movement of large polar molecules and ions
what type of protein does facilitated diffusion use
integral protein (channel)
does facilitated diffusion use ATP
no. it is a high concentration to low concentration
what is an integral protein again?
covers both sides of the membrane
what are the 3 characteristics of active transport
is movement from a low to high conc. gradient
is protein mediated transport (integral)
requires atp
what is a main example of an active transport
Na + / K+ Pump
and
Ca ++ Pump
what does the Na/K pump do
maintains high K+ in the cytoplasm and
low Na+ in the cytoplasm
what does the Ca++ pump do
maintains low Ca++ in the cytoplasm
what percentage of a cells supply of energy is used to maintain gradients
40 %
What does vesicular transport involve
vesicles
what are vesicles
membrane bound structures inside a cell
Does vesicular transport require ATP
Yes, it is active transport
what does vesicular transport do that it requires ATP
moves vessicles and or the cell membrane
fuses membrane just properly of phospholipid membraine
what is exocytosis in relation to and what does it do
movement out
vesicular transport
what is endocytosis in relation to and what does it do
movement IN
vesicular transport
what are the 2 types of endocytosis
pinocytosis and
phagocytosis
what is pinocytosis reffered to
cell drinking
what is phagocytosis refferred to
cell eating
what do selectively permeable membranes do
allow some particles to cross while restricting others
what does diffusion tend to eliminate
concentration gradients
what happens when different solute concentrations exist across a selectively permeable membrane
osmosis moves water such that an isotonic condition is established
can active transport mechanisms maintain concentration gradients?
yes
