The Plasma Membrane and Energy Flashcards
Fluid Mosaic Model
States that a membrane is a fluid structure with a “mosaic” of various proteins embedded in it. The fluid part: phospholipids. The mosaic part: embedded proteins.
Selective Permeability
The plasma membrane exhibits permeability. It allows some substances to cross it more easily than others.
Membrane Fluidity
Phospholipids in the plasma membrane can move within the bilayer. The type of hydrocarbon tails in phospholipids affects the fluidity of the plasma membrane.
Membrane Protein
Proteins that are part of, or interact with biological membranes.
Integral Membrane Proteins
Penetrate the hydrophobic core of the lipid bilayer.
Transmembrane
Completely span the membrane. All the way across.
Unilateral
One fusing membrane needed to be present.
Peripheral Membrane Proteins
Are loosely bound to the surface of the membrane. Usually held in place by the cytoskeleton elements.
Glycolipids
Extracellular surface of lipids.
Glycoproteins
Extracellular surface of proteins
Passive Transport Aquaporins
Transports water across cell membranes in response to osmotic gradients created by active solute transport.
Simple Diffusion
Is the net movement of molecules from a region of high concentration. Movement of small or lipophilic molecules (e.g. O2, CO2, etc.)
Concentration Gradient
This occurs when a solute is more concentrated in one area than another.
Facilitated Diffusion
Passive movement of molecules across the cell membrane via the aid of a membrane protein. Movement of large or changed molecules via membrane proteins (e.g. ions, sucrose, etc.)
Carrier Proteins
Integral glycoproteins that bind a solute and undergo a conformational change to translocate the solute across the membrane.
Osmosis
Is the net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (until equilibrium is reached).
Hypertonic
Solutions with a relatively higher osmolarity are categorized as hypertonic (high solute concentration –> gains water).
Hypotonic
Solutions with a relatively lower osmolarity are categorized as hypotonic (low solute concentration –> loses water).
Isotonic
Solutions that have the same osmolarity are categorized as isotonic (same solute concentration –> no net water flow)
Osmoregulation
Response of cells sensing a difference in osmotic pressure between the interior and exterior.
Turgid
Refers to cells or tissues that are swollen from water uptake.
Flaccid
The plasma membrane is not pressed tightly against the cell wall.
Active Transport
Uses energy to move molecules against a concentration gradient.
Sodium-Potassium Pump
An integral protein that exchanges 3 sodium ions (moves out of the cell) with two potassium ions (moves into the cell).
Proton Pump
A special kind of transporter that pushes hydrogen ions form areas of low concentration to areas with high concentration.
Electrogenic Gradient
The combination of the concentration gradient and voltage that affects an ion’s movement is called the electrochemical gradient.