BSI Lecture 12 Membrane Transport Flashcards
the distribution of important substances in intracellular vs extracellular are _______.
asymmetrical
An asymmetrical distribution indicates some form of _____ or _____ _______
concentration; extruding mechanism
What 2 types of molecules can pass through the cell membrane? (Groups)
1) Small hydrophobic molecules (O2, CO2, N2, Benzene)
2) Small uncharged polar molecules (H2O, glycerol, ethanol)
Larger uncharged polar molecules can easily cross the membranes. T or F
False, large uncharged polar molecules cannot easily pass through the membrane
Can ions pass easily across the membranes?
No, ions or atoms that contain a charge cannot pass through the membrane
A substance diffuses from an area of ____ concentration to ____ until a uniform concentration is achieved.
high; low
Diffusion can only occur in ___ or ___ phases.
liquid; gas
In water-based biological systems _____ is rapid but the path is convoluted as substances collide frequently.
diffusion
Diffusion is effective over long (intracellular/cellular) but not over short distances. T or F
False, diffusion is better over smaller distances (1mm in diameter or less diffusion of O2 is sufficient)
Diffusion time _______ by the square of the distance but _____ with increased area.
increases; decreases
Diffusion time decreases the greater the concentration difference (greater potential energy). T or F
true
Diffusion is more rapid the smaller the substance. T or F?
true
Diffusion movement is due to ______ energy and therefore increases as temperature increases. Increased viscosity can also be a significant
kinetic
When a concentration difference occurs across a membrane but the substance/solute is impermeable, WATER will move in the opposite direction in an attempt to equalize the concentrations, this is known as ______
osmosis
Is osmosis energetically favorable?
yes
Osmotic pressure depends on the ______ of solute particles only.
number
A Molar solution of a substance that does not dissociate, exerts an osmotic pressure of ____.
1 osmole
Dissociation into two ions, (as happens when NaCl is dissolved), ________ the osmotic pressure.
doubles
What are the ways water can pass through the membranes.
1) it can pass directly through the membrane
2) Through hydrophilic “binding sites” of transporter/”pumps”
3) The aqueous “cores” of ion channels
4) Aquaporins
The ______ pressure of bodily fluids, including cytoplasm is strictly regulated.
osmotic
_________ solutions will move water out of cells and cause them to shrink.
hypertonic
_________ solutions will move water into cells and cause them to swell or even burst/lyse.
hypotonic
________ refers to equal osmotic pressure.
isotonicity
Isotonicity must be maintained; what perform this task?
ion pumps
Because of water’s permeability it cannot be directly pumped/transported but must follow changes in osmotic pressure: typically NaCl is _____ and water _____.
pumped; follows
______ exert osmotic pressure, (aka oncotic osmotic pressure), and this can be a significant factor especially in fluid exchange in capillaries
proteins
________ pressure, (aka blood pressure), forces water out of capillaries but the oncotic pressure of the plasma proteins draws water back typically resulting in very little net fluid loss to the tissues.
hydrostatic
To move non-permeable solutes across membranes requires some form of _______ _______ that permits movement of ions or molecules across the lipid bilayer.
transport system
Transmembrane proteins can either form _____ channels or _________/pumps.
aqueous; transporters
Aqueous channels typically allow ions to flow ______ their electrochemical gradients.
down
Ion flow not only depends on concentration differences but also the _______ potential across the membrane.
electrical
If the flow is down the concentration or electrochemical gradient it is termed passive or facilitated transport and requires no energy, what supplies the energy?
the gradient supplies the potential energy
The flow against the concentration or electrochemical gradient it is termed ______ _______ and requires energy (usually ATP)
active transport
If _____ _____ of one solute is linked to the transport of another solute it is said to be coupled.
passive transport
If an active transport of one solute is linked to the transport of another solute it is called _______ _______ _______..
secondary active transport
Transport of a substance in one direction is termed ____
uniport
Transport of two or more substances in the same direction is termed _______
symport
Transport of two or more substances in opposite directions is termed ______
antiport
If _______ ________ is maintained by either transporting equivalent positive and negative ions, (for example Na+ with Cl- as in many epithelial cells), or exchanging ions with the same charge, (HCO3- out/Cl- in as in red blood cells), only the concentration gradient matters.
electrical neutrality
Unlike for membrane-permeable substances, transported substances rely on a finite number of transporting proteins and therefore are subject to _____ _______
saturation kinetics
Comparing the osmotic pressure of molar solutions, which solute would exert the least pressure?
A. One that dissociated fully
B. One that partially dissociated
C. One that did not dissociate
C. One that did not dissociate
Moving ions out of a cell will do what to its osmotic pressure?
A. Increase it
B. Not change it
C. Decrease it
C. Decrease it
Diffusion of a freely membrane permeable substance exhibits saturation kinetics?
A. True
B. False
B. False
Transport utilizing a carrier exhibits saturation kinetics?
A. True
B. False
A. True
Ion channels do not exhibit saturation kinetics?
A. True
B. False
A. True
Which direction of net flux does diffusion through lipid bilayer go?
High to low concentration
Diffusion through the bilayer is at equilibrium state or steady state.
Equilibrium
Diffusion through the bilayer, does it use integral membrane protein.
no
Diffusion through the bilayer, does it produce maximum flux at high concentration?
no
Diffusion through the bilayer, is it chemical specific?
no
Diffusion through the bilayer, does it use energy and source?
no
What are the typical molecules using diffusion through the bilayer?
Nonpolar: O2, CO2, fatty acids
Facilitated diffusion, what is the direction of net flux?
high to low concentration
Facilitated diffusion, is it at _____ or at steady state?
equilibrium
Facilitated diffusion, does it use integral membrane protein?
yes
Facilitated diffusion, does it achieve maximal flux at high concentration.
yes
Facilitated diffusion, does it use energy and source?
no
Facilitated diffusion, what are the typical molecules?
polar: glucose
Primary active transport, what is the direction of net flux?
low to high concentration
Primary active transport, is it a equilibrium or at steady state?
steady state
Primary active transport, does it use integral membrane protein?
yes
Primary active transport, does it achieve maximal flux at high concentration?
yes
Primary active transport, are they chemical specific?
yes
Primary active transport, do they use energy and source?
yes, ATP
Primary active transport, what are the typical molecules?
Ions: Na+, K+, Ca2+, H+
Secondary active transport, what is the directional of net flux?
Low to high concentration
Secondary active transport, is it a equilibrium or steady state?
steady state
Secondary active transport, does it use integral membrane protein?
yes
Secondary active transport, does it achieve maximal flux at high concentration?
yes
Secondary active transport, are they chemical specific?
yes
Secondary active transport, does it use energy and source?
yes, often ion gradient (Na+)
Secondary active transport, what are the typical molecules?
Polar: amino acids, glucose, and some ions
