exam 2 Flashcards
movement with concentration gradient
high -> low
passive diffusion
movement against concentration gradient
low -> high
active transport
what occurs in basic transport until equilibrium is reached?
diffusion
diffusion of 1 substance does or does not interfere with diffusion of another substance in the same solution?
does NOT
net movement of diffusion depends on what 3 things?
concentration gradient
particle size
permeability of a compound
rate of diffusion of lipid soluble molecules through lipid bilayer is also dependent on?
degree of lipid solubility
diffusion of water and other lipid insoluble compounds happens through?
protein channels
what 2 things determine passage through protein channels in diffusion?
pore diameter and electric charge
electric signals that regulate diffusion using channel proteins are?
voltage-gated channels
chemicals that bind channel proteins are?
ligand-gated channels
in ligand gating, binding a molecule may
open or close the gate
example of ligand gated channel
acetylcholine binds to ACH channel opening the channel to positive or uncharged molecules
in facilitated diffusion, each carrier protein has a specific affinity for
binding a molecule
when can you max out transporters (Vmax) in facilitated diffusion?
if available transport proteins are bound to substrates (solute)
in facilitated diffusion, carrier proteins are?
saturated
example of facilitated diffusion
movement of glucose and most amino acids
saturation of a carrier protein is reflected by leveling off
the rate of transport
Km is a measurement of?
solute concentration that will give 1/2 Vmax
transfer of liquid through a semipermeable membrane that does not allow solutes to pass is called
osmosis
in osmosis, water passes through ______ in plasma membrane
aquaporins (water pores)
osmosis moves from?
high to low
pressure applied to stop the flow of water to the side of highest concentration is called
osmotic pressure
when osmotic pressure is the same inside and outside the cell
isotonic
movement of water into the cell which increases cell volume
hypotonic- osmotic pressure is greater in cytosol
movement of water out of the cell and cells shrink
hypertonic- osmotic pressure is greater in extracellular fluid
carrier proteins called ATPases are necessary in
active transport
movement of ions making ion gradient which powers?
secondary active transport
examples of active transport
uptake of glucose into the intestines and uptake of ions
secondary active transport is not driven by ATP but instead by
ion concentration gradient (from primary transport)
transporters of secondary active transport do not have
ATPase activity
the larger alpha protein of the sodium potassium pump has how many binding sites for sodium and potassium and where are they in the cell?
sodium- 3 binding sites INSIDE the cell
potassium- 2 binding sites OUTSIDE the cell
energy released from sodium-potassium pump causes a conformation change in the?
carrier protein
sodium is pumped where and potassium is brought where?
sodium is pumped to the outside and potassium is brought inside
secondary active transport symporters are
glucose and amino acids
secondary active transport anti porters are
calcium and hydrogen
transport molecules in the SAME direction across plasma membrane are called
symporters
with co transport/symporters and anti porters, molecule 1 is moved __1_____the gradient while molecule 2 is actively transported __2_____ the gradient
- with (high to low)
2. against (low to high)
sodium-glucose transport is an example of
symport or co-transport
transport molecules in the OPPOSITE direction across the plasma membrane
antiporters
example of antiporter
sodium-calcium antiporter in cardiac muscle
glucose transport occurs by?
facilitated diffusion and secondary active transport
active transport of glucose is used when glucose concentration in cell is
higher than extracellular
secondary active transport in glucose transport uses
sodium-glucose transport proteins (SGLT)
absorption of glucose into the Si happens when sodium and glucose are transported
into the enterocyte/cell (symport/co-transport)
energy for absorption of glucose into the SI is derived from
electrochemical gradient of sodium created by sodium-potassium ATPase
4 steps of glucose active transport
- sodium binds carrier protein
- glucose binds carrier protein
- carrier proteins release glucose and sodium into enterocyte
- sodium is pumped out of enterocyte and potassium is pumped in using ATP
GLUTs transport glucose from high to low concentration in
facilitated diffusion of glucose
rate of transport of glucose in facilitated diffusion is based on
amount of glucose available and # of GLUT proteins
GLUT 2 proteins are able to transport in
both directions across membranes
GLUT 2 proteins are located in
intestines
GLUT 4 proteins are located in
muscle and adipose tissue
insulin-INsensitive facilitated transport of glucose requires
concentration gradient of glucose
insulin-INsensitive facilitated transport of glucose uses which proteins?
GLUT 1, 2, 3, and 4
insulin-INsensitive facilitated transport of glucose is found in?
most tissue RBC WBC liver brain cells etc
after a sugar rich meal, glucose =
active transport & facilitated diffusion
GLUT 2 transports glucose, galactose and fructose
out of enterocyte and into portal blood
more carbs eaten =
more GLUT 2 in apical membrane
GLUT 2 concentrations increased in response to?
diet
insulin-sensitive facilitated transport of glucose is found in
skeletal muscle
adipose tissue
intestinal epithelia
insulin-senstive facilitated transport of glucose uses which proteins?
GLUT 2 and 4
following insulin secretion, insulin pulls GLUT2 from ______ & ________ to decrease glucose absorption
brush border & basolateral membrane
beta cells are destroyed and no insulin is released in
type 1 diabetes
insulin resistance= failure of cells to listen to insulin
type 2 diabetes
following insulin secretion in type 2 diabetes insulin regulation of GLUT2 does or does not function in insulin resistance?
does NOT
most drugs must be transported to
target tissue
the vast majority of drugs use the __________ to move throughout the body
circulatory system
solute carriers (SLCs) can be used to transport both
xenobiotic and non-xenobiotic drugs
ATP-binding cassette transporters (ABCs) use
primary active transport
SLCs of drug transport mostly transport
INTO cells
ABCs of drug transport mostly transport
OUT of cells
which type of ABC transporter is the most well understood involved in multi drug resistance?
ABCB1
expression of ____ is upregulated in response to the presence of cell death inducing ______
ABCB1, chemicals/drugs
what can also interfere with other substrates in transports under normal conditions?
ABCB1 upregulation
The Sodium-Potassium ATPase pump is an example of a _____ -class transporter
P-class
transmembrane proteins that bind to specific compounds and translate a signal/message into a cell are called
receptors
What drives the transport of glucose via SGLT transport proteins?
ion gradient of sodium
Which type of membrane transport gate is controlled by the charge across the cell membrane?
voltage gated
