Eukaryotic Plasma Membrane Flashcards

Flashcards for reviewing the structure and function of the eukaryotic plasma membrane.

Plasma Membrane

The outer living boundary of all cells, also called the plasmalemma/cell membrane.

Lipids in Plasma Membrane

Main component of the plasma membrane that gives the membrane its fluid properties.

Cholesterol

Lipids with no fatty acids found in animal cell membranes

Phytosterols

Lipids with no fatty acids found in plant cell membranes

Glycolipids

Lipids attached to carbohydrates

Phospholipid Molecule

Contains a phosphate-containing head that is hydrophilic and fatty acid tails that are hydrophobic.

Adhesion Proteins

Helps one cell adhere to another cell or to a protein component of an extracellular matrix.

Communication proteins

Proteins in the plasma membrane of one cell match up with identical proteins in the plasma membrane of an adjoining cell.

Receptor Proteins

Receive and respond to stimuli, such as hormones.

Recognition Proteins

Identity tags by which cells recognize self from non-self.

Passive Transport Proteins

Channels that passively enable one or more substances to cross a membrane.

Active Transport Proteins

Also called ATPase pumps, use energy provided by ATP to actively pump solutes across the membrane.

Fluid Mosaic Model

Description of the arrangement of molecules in the plasma membrane, where it's a mosaic of several types of molecules constantly moving in a fluid bilayer of phospholipids.

Plasma Membrane Functions

Defines cellular boundaries (compartmentalization), controls movement (transport) of substances, detects external signals and self-recognition, mediates cell-to-cell communication, and serves as sites for specific functions.

Diffusion

The net/overall movement of like molecules or ions from an area where they are more concentrated to an area where they are less concentrated, till equilibrium is reached.

Concentration Gradient

The number of molecules or ions in one region is different from the number in another region.

Passive Transport

Does not need energy and requires presence of transporter protein; net movement is down a concentration gradient.

Active Transport

Needs energy (as ATP) and requires presence of active transporter protein to pump solutes against its concentration gradient.

Exocytosis

Large particles or hormones are exported out of the cell when a vesicle fuses with the plasma membrane.

Endocytosis

Large particles, like food, are taken into the cell when the plasma membrane sinks inwards and wraps around the particles.

Receptor-Mediated Endocytosis

Specific solutes are taken in by binding to receptor proteins.

Bulk Phase Endocytosis

Non-specific solutes are taken in, such as ingestion of solutes in fluid (pinocytosis).

Phagocytosis

Entrapment of food particles

Membrane Cycling

Occurs when endocytosis withdraws membrane and exocytosis replaces membrane, continually replacing and withdrawing patches of the plasma membrane.

Osmosis

The movement of water across selectively permeable membranes down a water concentration gradient.

Tonicity

Refers to the relative concentrations of two fluids.

Hypotonic

A solution containing fewer solutes than the one in question

Hypertonic

A solution containing more solutes than the one in question

Isotonic

Solutions have the same concentrations

Hydrostatic Pressure

Pressure the volume of water in a cell exerts against the enclosing/boundary structures

Osmotic Pressure

Internal fluid pressure that prevents inward diffusion of water.

Osmoregulation

Active regulation of the osmotic pressure of a cell’s fluids.

Plasmolysis

Process where a plant cell loses water when placed in a hypertonic solution.