Exam 3 Notes Flashcards
Selective permeability allows for what?
allows for the separation and exchange of materials across the plasma membrane
influx
flowing in of materials
efflux
flowing out of materials
net flux
net flux = influx-efflux
the amount of movement inside or out of the cell
Diffuson
movement of material from high concentration to low
for uncharged molecules diffusion depends on the ______ _______.
concentration gradient
For charged molecules diffusion depends on what?
both the concentration gradient and electrochemical gradient
Aquaporins
specialized protein channels that allow for passive movement of water across the membrane
What is lipid permeability determined by?
size and polarity
hypertonic
Solute concentration is higher outside the cell than it is in.
osmosis
diffusing of water from an area of high water concentration to low water concentration
or
diffusion of water from an area of low solute concentration to an area of high solute concentration
across a semi permiable membrane
what happens if a cell is placed in a hypotonic solution?
there will be a net flow of water into the cell and it will swell
why are aquaporins prevalent in the kidneys?
Aquaporins are prevalent in the kidneys due to their crucial role in facilitating water reabsorption, urine concentration, and regulation of water balance, essential for maintaining fluid and electrolyte homeostasis in the body.
Which of the following compounds can diffuse easily across a phospholipid bilayer?
a) Ca2+
b) O2
c) Glucose
d) Cl–
e) All of these
B
Steroid hormones would cross the membrane by:
A) Simple diffusion
B) Facilitated diffusion
C) Osmosis
D) Active transport
E) Endocytosis
A
Paramecium have contractile vesicles that continuously expel water from the cell. This suggests that they live in a(n) __________ environment.
A. Hypotonic
B. Isotonic
C. Hypertonic
A
Does the lipid bilayer like charged substances?
no
Ions cross membranes through what?
ion channels
What are the 5 types of ion channels?
gated, always open, voltage gated, ligand gated, mechano gated
what kind of ion channel is is always open?
leak channels
what kind of ion channels state depend on difference in charge(ions) between the inside and the outside
voltage gated
what kind of ion channels conformation depends on binding to a specific molecule(ligand)?
ligand-gated
what kind of ion channels conformation depends on mechanical forces (ex. stretch)?
mechano-gated
what kind of ion channel can exist in either an open or a closed conformation
gated
An effluc of K+ would be driven by ______ ______, but opposed by _______ ________
concentration gradient, electrical gradient
go back to ionic concentrations of typical mammalian cells
