Membrane Transport & Communication Flashcards
what do membranes do (4)
1)create barriers which:
protect cells from external environment and some internal substances
2)are actively involved in the movement of molecules into and out of cells
3)provide the wiring for electrical signaling
4)provide the site for many signaling processes
what is membrane strucutre
phospholipid bilayer
hydrophilic head
hydrophobic tail
what is bulk transport used for
transporting macromolecules
what is exocytosis
moving out of the cell
what is endocytosis
moving into the cell
what are the 3 types of endocytosis
receptor-mediated (viruses)
Pinocytosis (drinking fluid)
phagocytosis (eating)
what is cellular transport responsible for
movement of smaller number of molecules across the cell membrane
what are the 2 energy potentials for cellular transport
concentration gradient
cleavage of ATP high energy phosphate bonds
what are the two basic classes of transport
passive transport
active transport
what are the 3 types of passive transport
simple diffusion- osmosis
channel mediated diffusion
carrier mediated diffusion
what are channel and carrier mediated diffusion commonly referred to
facilitated diffusion
what are the 2 types of active transport
primary (1st)- uses ATP
secondary (2nd)- uses concentration gradient
explain simple diffusion
molecules pass through cell membrane
typically lipid based and nonpolar
explain facilitated diffusion (channel mediated)
and what are the two types of channel mediated diffusion
includes a membrane spanning protein channel
Leak channel
Gated channel
explain leak channel
always open typically charged inside molecules of opposite charge pass through
explain gated channel
voltage gated: open by electrical signals
ligand gated: open when ligand binds
explain carrier mediated
includes a membrane spanning protein
protein actively binds molecules and carriers them down their concentration gradient.
carrier proteins act like enzymes- lock and key
Active transport
explain primary
a pump protein is powered by ATP to move molecules against their concentration gradient
Active transport
explain secondary
a pump protein is powered by one molecule concentration gradient to move a different molecule against its concentration gradient
what are the 2 terms that can describe all active transporters
antiport
symport
define antiport
molecules move in opposite direction
define symport
molecules move in same direction
what are the two ways that cells communicate
electrical or chemical
what is an example of chemical signals
circulatory system
what is an example of electrical signals
nervous system
how does electrical signals work
very quick and targeted response
how does chemical signals work
hormonal signals
signaling pathways begin with the binding of a what to a receptor
binding of a ligand to a receptor
define ligand
a molecule that binds to a receptor
define receptor
a protein that binds a ligand and creates a response.
