Ch.7: Membrane & Movement of Molecules Flashcards
Amphipathic molecules
contains hydrophobic and hydrophillic regions
Cholesterol (steroid) acts as a
temperature buffer. Warm temps, it restrains movement, cool temperatures, it maintains fluidity within the cell membrane
Peripheral proteins
Integral Proteins
Peripheral proteins are bound to the surface of the membrane. Hydrophilic
Integral Proteins penetrate the hydrophobic core.
Diffusion
is the tendency for molecules to spread out into available space. Does not require energy called passive transport
concentration gradient
Substances diffuse from high to low concentration, down their concentration gradient
Osmosis
is the diffusion of water across a selectively permeable membrane.
Isotonic solution:
Equal solute/water concentration as inside of the cell. No net water movement across the membrane.
Tonicity
the ability of a solution to cause a cell to gain or lose water
Hypertonic solution
Solute concentration is greater than inside the cell. Cell loses water. Cells shrivel
Hypotonic solution:
Solute concentration is less than that inside the cell. More water, less solute., gains water.
Osmoregulation
the control of water balance for life to survive., for ex: single celled organisms like protists.
Facilitated diffusion
transports proteins and speeds the passive movement of molecules across the membrane.
Channel proteins
like aquaporins (for water) facilitate the passage of molecules or ions through a hydrophilic channel that acts as a tunnel.
Carrier proteins
bind to molecules and change shape to shuffle them across the membrane. Specific for the substance it moves.
Active transport
moves substances against the concentration gradient, from LOW to HIGH concentration. REQUIRES ENERGY, ATP. Not equalibrium ex. Sodium-potassium pump
Membrane potential
the voltage difference across a membrane. -
The inside of the cell has a negative charge.
Electrogenic pump
a transport protein that generates voltage across a membrane
Proton pump
is found in plants, fungi, and bacteria. (animals have sodiumpp)
vesicles
Large molecules like polysaccharides and proteins cross the membrane in bulk via vesicles
Exocytosis
when transport vesicles migrate to the membrane, fuse with it, and release their contents
Endocytosis
The cell takes in macromolecules by forming vesicles from the plasma membrane.
Phagocytosis
is a cell engulfing a particle in a vacuole. formes food vacuoles
Pinocytosis
molecules taken up thru extracellular fluids being gulped up into tiny vesicles
receptor mediated endocytosis
binding of ligands to receptors triggers vesicle formation
