Lecture 2: Membrane Transport Mechanisms Flashcards
Which of the following would have to be a transmembrane protein?
A receptor protein
A protein binding to the cytoskeleton
A channel protein
A phosphorylase
A channel protein
Which organelle is directly associated with synthesis of proteins for secretion?
Rough endoplasmic reticulum
Pits coated with what, are associated with endocytosis?
Clathrin
Which process does not require the presence of mitochondria? And what does it do?
Glycolysis - breakdown of glucose to pyruvic acid
Which of the following transport mechanisms requires energy, other than kinetic energy?
Osmosis
Diffusion
Active transport
Facilitated diffusion
Active transport
Which ion is most concentrated in the extracellular matrix?
Sodium
The Na/K pump is an example of which kind of transport?
Primary active transport
The sodium-glucose pump is an example of what kind of transport?
Secondary active transport
The sodium-calcium pump is an example of which kind of transport?
Secondary active transportation
Glucose transporters employ which type of transport?
Facilitated diffusion
What mechanism will likely be used to move water from an extracellular environment across an epithelial cell layer, into the extracellular matrix on the opposite side of the epithelial cell layer?
Sodium channels and sodium ATPase pumps
Water then follows via osmosis
movement of particles from areas of high concentration to low concentration
diffusion
what is the difference between diffusion and net diffusion?
net diffusion is across a permeable membrane
movement of a solvent from high to low concentration areas, across a semipermeable membrane
osmosis
solvent is water
describe how osmotic pressure is built up
water mvt across a membrane will cause a build up of water on one side and an increase in pressure on the other side
what does effective osmotic pressure tell us?
different things can pass through the same membrane with different amounts of ease
a type of protein that opens a link between the inside and outside cell matrix
an integral protein = channel protein
what are the two categories of transport?
energy independent
or
dependent
types of energy independent transport
diffusion
osmosis
facilitated diffusion
non-gated channels
always open
examples: aquaporins, ion channels
gated channels
open under specific conditions
ligand gated
voltage gated
type of transport that requires ATP
energy dependent
active transport
what type of transport is the only means of transportation that is not carrier mediated?
simple diffusion
what is involved in calculating diffusion?
flow rate
permeability
area
concentrations
list substances that can diffuse across the phospholipid bilayer
oxygen
CO2
nitrogen
alcohols
what factors can increase permeability of a substance across a membrane?
increase lipid solubility
decrease size of solute
decrease membrane thickness
what differentiates facilitated diffusion from simple diffusion?
facilitated is carrier mediated
requires a uniporter
occurs down an electrochemical gradient
the maximum particles that can be carried at one time in facilitated diffusion
Vmax
is carrier mediated transport stereospecific?
yes
different transports are required for different molecules
describe the rate of simple diffusion
non-gated
flows at a constant rate
describe the rate of facilitated diffusion
exponential rate that increases towards Vmax
movement of particles against a gradient
active transport
transport that utilizes ATPase as a transporter
primary active transport
transport that utilizes ATP and multiporters
secondary active transport
primary active transport
energy derived from direct breakdown of ATP
ATPase serves as transporter, up it’s electrochemical gradient
secondary active transport
one particle is going up it’s gradient and the second is going down it’s gradient
primary creates conc. differences, energy built up from this differences is the power used for secondary
multiporters used
types of multiporters
symporters - 2 particles in same direction
antiporter - 2 particles in opposite direction
what is the most common solute in secondary active transport?
sodium
if sodium moves down it’s electrochemical gradient, why is this classified as secondary active transport?
because the energy given off by it’s mvt down, powers the transport of another particle up it’s gradient
if sodium is moving down it’s electrochemical gradient, what direction is it going?
from extra- to the intracellular matrix
sodium/calcium antiporters move 3 Na for every 1 Ca particle. why does it take 3 Na to move 1 Ca?
because sodium is much smaller
calcium is much heavier
____ sodium particles are moved for every ____ potassium particles.
3 Na per 2 K
what is the difference between uniporter and multiporter?
uniporters can only transport one particle at a time
describe potassium channels
non-gated channels have carbonyl oxygens that serve as selectivity filters function to ensure on K+ can get through even though Na is smaller than K
how can body compartment volumes be altered?
by mvt of water
we have no mechanism to directly move water
so we move Na and water follows it
cells in which an action potential can be induced
excitable cells
ex. - neurons and muscle cells
neurons do not have ____ gated channels in the cell membrane.
voltage gated channels
dendrites are characterized by the presence of _____ gated channels, and can conduct ____ potentials.
ligand gated channels
local potentials
the _____ of the axon contains voltage gated channels.
axolemma
what region of the axon contains synaptic vesicles and mitochondria?
terminal boutons in the distal axon telodendria
which part of a neuron is capable of developing an action potential?
axolemma
the carrier proteins of primary active transport are commonly referred to as ?
ATPase pumps
another term for symporters
co-transporters
another term for antiporters
counter-transporters
