Chapter 3 Membrane Flashcards
Diffusion
the passive net of movement of a substance from a high-low concentration, to reach an equilibrium.
-Disperse until evenly distributed in the space, moving down a concentration gradient.
Simple diffusion
is when smaller, non-polar solutes diffuse across the phospholipid bilayer.
-The rate of diffusion is proportional to a molecule’s concentration gradient.
Osmosis
a passive diffusion type involving free water molecules moving through a semi-permeable membrane.
-Travels from low solute concentration to a high solute concentration.
Semi-permeable membrane
where water can cross, but solutes cannot
osmolarity
the total concentration of solutes in solution.
hypertonic
when the solute concentration is high
isotonic
when the solute concentration is equal
hypotonic
when the solute concentration is low
facilitated diffusion
the passive movement of molecules across a membrane through specific transmembrane integral proteins.
-Channel proteins allow smaller, polar molecules to diffuse, a narrow water-filled pore creates a hydrophilic channel.
Protein channels
open only in response to certain stimuli to allow diffusion
Carrier proteins
allow larger, non-polar molecules to diffuse, by changing its shape
active transport
the active movement of molecules against their concentration gradient.
-By a carrier protein.
ATP
made of an adenine base, 5 carbon and 3 phosphate.
-Produced in mitochondria by cellular respiration
-Diffuses into cells to places that need energy
-Broken into ADP and Pi, which diffuse back into mitochondria to turn to ATP
bulk transport
the active movement of a large cell, by enclosing it in a membrane sac.
Exocytosis
when large molecules are secreted from a cell by the fusion of a vesicle.
-Vesicles containing the substance fuse to the cell membrane which releases the substance.
