Plasma Membrane Structure and Function

A set of flashcards covering key terms and concepts related to the structure and function of the plasma membrane, ideal for exam preparation.

Plasma Membrane

The thin, flexible outer boundary of a cell that acts as a barrier between internal and external environments.

Eukaryotic Cells

Cells that contain a nucleus and are enclosed by a plasma membrane.

Cytosol

The aqueous gel that fills the cell and surrounds the organelles.

Organelles

Subcellular structures with specific functions, can be membranous or non-membranous.

Membranous Organelles

Organelles that are enclosed by membranes such as the endoplasmic reticulum and Golgi apparatus.

Non-Membranous Organelles

Organelles without membranes, including cytoskeleton and ribosomes.

Phospholipid Bilayer

The fundamental structure of the plasma membrane, consisting of two layers of phospholipids.

Selective Permeability

The property of the plasma membrane that regulates the passage of substances into and out of the cell.

Glycocalyx

The protective outer layer formed by carbohydrates attached to lipids and proteins on the cell membrane.

Fluid Mosaic Model

Model that describes the plasma membrane as a mosaic of various components that move freely within the lipid bilayer.

Integral Proteins

Proteins that are embedded within the lipid bilayer of the plasma membrane.

Peripheral Proteins

Proteins that are loosely attached to the surface of the membrane and do not extend into the lipid bilayer.

Transmembrane Proteins

Integral proteins that span the entire thickness of the lipid bilayer.

Membrane Fluidity

The ability of lipids and proteins in the plasma membrane to move and change positions, behaving like a two-dimensional fluid.

Cholesterol

A lipid that helps regulate the fluidity of the plasma membrane.

Diffusion

The passive movement of molecules from an area of higher concentration to an area of lower concentration.

Facilitated Diffusion

Passive transport process that uses channel or carrier proteins to move molecules across the membrane.

Active Transport

The process that requires energy to move molecules against their concentration gradient.

Na+/K+ Pump

A primary active transport mechanism that pumps sodium out of the cell and potassium into the cell.

Symport

Transport of two different molecules in the same direction across a membrane.

Antiport

Transport of two different molecules in opposite directions across a membrane.

Endocytosis

The process by which cells internalize substances by engulfing them in a membrane.

Exocytosis

The process by which substances are expelled from the cell via vesicles that fuse with the plasma membrane.

Receptors

Proteins that bind to signaling molecules and initiate a cellular response.

G Protein-Coupled Receptors (GPCRs)

The largest family of receptors that activate intracellular signaling pathways upon binding to a receptor.

Ligand-Gated Channels

Ion channels that open in response to the binding of a signaling molecule.

Channel-Linked Receptors

Receptors that allow ions to cross the plasma membrane when a ligand binds.

Catalytic Receptors

Receptors that have enzymatic activity and can catalyze specific reactions upon binding of a ligand.

Lipid Rafts

Microdomains within the membrane that are rich in cholesterol and play roles in signaling.

Clathrin-Coated Pits

Specialized regions of the membrane involved in receptor-mediated endocytosis.

Tight Junctions

Cell junctions that prevent the passage of molecules between cells.