Membrane transport 2 Flashcards
is the outermost component of a cell and forms the boundary
between material inside and outside material
Cell Membrane
acting as barrier that
determines what moves
into and out of the cell
Cell membrane
The cell membrane has ____________, which allows only
certain substances to pass in and
out of the cell.
selective
permeability
Some materials can pass
through, while others are
excluded
Selectively permeable barrier
are substances contributing to body mass that are found outside the cells.
Extracellular substances
High concentration inside the cell
Enzymes, glycogen, potassium
High concentration outside the cell
Sodium, calcium, and chloride
are pores within a lipid bilayer. The channels can be formed by protein complexes that run across the membrane or by peptides. They may cross the cell membrane, connecting the cytosol, or cytoplasm, to the extracellular matrix.
transmembrane
protein channels
Some substances, like O2 and CO2,_______
can pass
directly through the cell membrane’s
phospholipid bilayer.
Some substances must pass through
_________ channels, such as Na+
through its channels.
transmembrane protein
The route of transport through the membrane
depends on the__________ of the
substance.
size, shape, and charge
Some substances require ________ to
transport them across the cell membrane, such as glucose.
carrier molecules
Some substances require a _______________
across the membrane.
vesicular transport
The vesicle ________ with the cell membrane
for transport.
must fuse
Membrane characteristics
Selectively permeable, asymmetric, amphiphilic
A molecule having both hydrophobic (nonpolar) and hydrophilic (polar) regions.
Amphiphilic
2 Basic methods of movement though cell membrane
Passive transport
active transport
homogeneous mixture of two or more components (ex: air that we
breath, fluid of plasma membrane, seawater, rubbing alcohol)
SOLUTION
dissolving medium; typically water in the body
SOLVENT
components in smaller quantities within a solution
SOLUTES
the difference in the concentration of a solute in a solvent between
two points divided by the distance between the two points.
CONCENTRATION GRADIENT
is the passive movement
of molecules from an area
of _________
high concentration to an
area of low concentration.
Molecules will move by diffusion if any of the following applies:
The molecules are small enough to pass through the membrane’s
pores (channels formed by membrane proteins) (FD)
The molecules are lipid-soluble (D)
The molecules are assisted by a membrane carrier (FD)
constantly
allow ions to pass through.
Leak channels
limit the
movement of ions across the
membrane by opening and
closing
Gated channels
is the diffusion of water
across a selectively
permeable membrane, such
as the cell membrane, from
a region of higher water
concentration to one of
lower water concentration
Osmosis
the pressure created by
water moving across a
membrane due to
osmosis.
Osmotic Pressure
_________, the higher the
osmotic pressure.
The more water
moving across the
membrane
proteins within the cell
membrane
Carrier molecules
move large, water-soluble molecules
or electrically charged ions across the cell membrane.
carrier-mediated transport
mechanisms
A molecule to be transported binds to a _________ on one side of the membrane.
specific carrier
molecule
Carrier-Mediated Transport Mechanisms includes
facilitated diffusion and Active transport.
Carrier-mediated transport mechanisms
exhibit ____________ meaning only specific molecules are
transported by the carriers.
specificity;
Facilitated diffusion does not require ______
ATP for energy.
Active transport does require ______
ATP for transport.
a carrier-mediated
transport process that
moves substances from an
area of high concentration
to an area of low
concentration with the help
of a transport molecule.
Facilitated Diffusion
against a concentration
gradient.
Active Transport
Active transport a carrier-mediated process
that moves substances
across the cell membrane
from regions of _____
lower
concentration to those of
higher concentration
The _________________
moves Na+ out of cells and K+
into cells.
sodium-potassium pump
Sodium potassium pump is necessary for ________
nerve impulses
the diffusing
substance moves in the same
direction as the transported
substance
Cotransport
the
diffusing substance moves in
a direction opposite to that of
the transported substance.
Countertransport
Large water-soluble
molecules, small pieces of
matter, and even whole
cells can be transported
across cell membranes in
membrane-bound sacs
called
vesicles.
uptake of material through
the cell membrane by the
formation of a vesicle.
Endocytosis
Types of Endocytosis
Receptor-mediated
Phagocytosis
Pinocytosis
occurs when a specific
substance binds to
the receptor molecule
and is transported
into the cell.
Receptor-mediated
Endocytosis
used for endocytosis
when solid particles are
ingested.
Phagocytosis (cell-eating)
engulfs large particles i.e.
bacteria or dead body
cells
engulfs large particles i.e.
bacteria or dead body
cells
protective mechanism,
not a means of getting
nutrients
Phagocytosis (cell-eating)
Functions of Phagocytosis (cell-eating)
used for endocytosis
when solid particles are
ingested.
engulfs large particles i.e.
bacteria or dead body
cells
protective mechanism,
not a means of getting
nutrients
smaller vesicles are formed,
they contain liquid rather than
solid particles
Pinocytosis (cell-drinking)
Plasma membrane forms a pit,
and edges fuse around droplet
of fluid
Pinocytosis (cell-drinking)
Plasma membrane forms a ______,
and edges fuse around droplet
of fluid
pit
Cell “______”: droplets of
extracellular fluid containing
dissolved proteins or fats
gulps”
Cell “gulps” droplets of
extracellular fluid containing
____________
dissolved proteins or fats
the process when secretory
vesicles move to the cell
membrane, where the
membrane of the vesicle fuses
with the cell membrane, and
the material in the vesicle is
eliminated from the cell.
Exocytosis
