Cell Membrane Structure and Transport Mechanisms

Comprehensive vocabulary flashcards covering membrane structure, types of cellular transport, tonicity, and membrane properties based on lecture notes.

Amphipathic

Having both a polar region and a nonpolar region.

Channel proteins

Donut-shaped proteins that act as gates and tubes that open and close to allow polar molecules to pass.

Marker proteins

Proteins in the cell membrane that identify the cell.

Receptor proteins

Proteins that transmit information in and out of cells and allow communication between cells.

Integral proteins

Proteins embedded in the phospholipid bilayer.

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

Diffusion of water through a selectively permeable membrane.

Carrier transport

Movement of materials through a cell membrane with the aid of proteins.

Facilitated diffusion

The transport of substances through a cell membrane with a concentration gradient with the aid of channel proteins.

Endocytosis

Process by which a cell takes material into the cell by infolding of the cell membrane creating a vesicle.

Exocytosis

Release of substances out of a cell by the fusion of a vesicle with the membrane.

Passive transport

Movement of molecules that does not require energy, from high concentration to low concentration.

Active transport

The movement of materials through a cell membrane using energy, from low concentration to high concentration.

Cell membrane

A cell structure made of phospholipids that controls which substances can enter or leave the cell.

Equilibrium

Equal movement of molecules through a membrane, creating a balance of dissolved solute in solutions inside and outside of cells.

Hypertonic solutions

Solutions that contain a higher percentage of solute than an environment separated by a membrane.

Hypotonic solutions

Solutions that contain a lower percentage of solute than an environment separated by a membrane.

Isotonic solutions

Solutions separated by a membrane and containing an equal concentration of solute and solvent.

Polarity

Partial charges created by the unequal sharing of electrons.

Hydrophobic

Molecules, such as nonpolar lipids, that are repelled by water.

Hydrophilic

Molecules that are attracted to water.

Cytolysis

The bursting of a cell due to high osmotic pressure.

Osmotic pressure

Pressure of water pushing on the cell membrane.

Turgor pressure

The pressure that water molecules in the vacuole of plant cells exert against the cell wall.

Plasymolysis

Wilting or shrinking of cells due to low osmotic pressure.

Solute

A substance that is dissolved in a solution.

Solvent

The substance in which a solute dissolves.

Solution

A mixture that forms when one substance dissolves another.

Water

Universal solvent in living organisms.

Vesicles

Small membrane sacs that specialize in moving products into, out of, and within a cell.

Phagocytosis and pinocytosis

Two types of endocytosis.

Concentration gradient

A difference in the concentration of a substance in an area.

Selectively permeable

A property of cell membranes that allows some substances to pass through, while others cannot.

Molecules that can pass through the cell membrane by diffusion

Examples include $O_2$, $CO_2$, and $H_2O$.

Molecules that cannot pass through the cell membrane by diffusion

Examples include $Na^+$, $K^+$, and glucose.

Phospholipids

Molecules composed of a phosphate group, a glycerol, and fatty acids.

Fluid Mosaic Model

Structural model of the cell membrane where various molecules are free to move sideways within a lipid bilayer.

Shape, size, and charge of molecules

Properties that determine the passage of molecules through the phospholipid bilayer.