Membrane Transport Proteins Flashcards
Passive Transport
movement of biochemicals and other atomic or molecular substances across cell membranes without need of energy input.
Active Transport
the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.
Diffusion
Net passive movement of particles (atoms, ions or molecules) from a region in which they are in higher concentration to regions of lower concentration. It continues until the concentration of substances is uniform throughout.
Membrane potential
Difference between the concentration of molecules and charge inside and outside the cell
Electrochemical Gradient
for an ion that can move across a membrane
Facilitated Diffusion
the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane via specific transmembrane integral proteins.
Channel Protein
allows the transport of specific substances across a cell membrane
Carrier Protein
protein that transports specific substance through intracellular compartments, into the extracellular fluid, or across the cell membrane
Primary Active Transport
requires the assistance of a type of protein called a carrier protein, using energy supplied by ATP.
Secondary Active Transport
meaning that one of the two substances is transported in the direction of its concentration gradient, utilizing the energy derived from the transport of such substance (mostly Na+, K+ or H+ ions) down its concentration gradient.
Endocytosis
taking in of matter by a living cell by invagination of its membrane to form a vacuole.
Phagocytosis
type of endocytosis. Endocytosis is a process through which a cell absorbs a particle, molecule, bacterium, or other type of matter by engulfing it.
Exocytosis (secretion)
Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane
important in expulsion of waste materials out of the cell and in the secretion of cellular products such as digestive enzymes or hormones.
why some molecules cannot use passive diffusion to cross membranes and must use
facilitated diffusion or active transport
Small molecules that are nonpolar (have no charge) can cross the membrane easily through diffusion, but ions (charged molecules) and larger molecules typically cannot.
The similarities and differences between channel proteins, carrier proteins, and
active transporters.
Difference between channel proteins and carrier proteins…. • Solutes diffuse through the pore of channel proteins, whereas career proteins bind solutes on one side of membrane and release it on the other side.
• Compared with channel proteins, carrier proteins have very slow transport rates (on the order of 1000 solute molecules per second).
• Unlike carrier proteins, channel proteins contain a pore, which facilitates the solute transportation.
• Unlike channel proteins, carrier proteins have alternate solute-bound conformations.
• Channel proteins are lipoproteins, while carrier proteins are glycoproteins.
• Carrier proteins can mediate both active and passive transport, while channel proteins can mediate only passive transport.
• Channel proteins are synthesized on ribosomes bound to endoplasmic reticulum, while carrier proteins are synthesized on free ribosomes in the cytoplasm.
• Carrier proteins can transport molecules or ions against the concentration gradient, while channel protein cannot.
• Carrier proteins move across the membrane, whereas channel proteins do notmove while transporting molecules or ions.
• Channel proteins only pass water soluble molecules, while carrier proteins transport both water soluble and insoluble substances.
