Cell Membrane Structure and Function

Vocabulary flashcards covering plasma membrane structure, fluidity, transport organelles, and membrane proteins based on lecture notes.

Plasma membrane

The selectively permeable outer boundary of a cell that regulates the entry and exit of materials.

Selective permeability

The characteristic of a membrane that allows small, nonpolar molecules like estrogen, $CO_2$, and $O_2$ to pass freely, while restricting charged or polar molecules.

Phospholipid

An amphipathic molecule composed of a polar hydrophilic head and nonpolar hydrophobic tails that forms the core structure of cell membranes.

Hydrophilic head

The polar region of a phospholipid that interacts favorably with water.

Hydrophobic tail

The nonpolar region of a phospholipid composed of fatty acid chains that repels water.

Fluid mosaic model

A structural model describing the membrane as a fluid bilayer of phospholipids embedded with a mosaic of proteins, glycolipids, and cholesterol.

Integral proteins

Proteins embedded within the phospholipid bilayer, penetrating it either partially or completely across the membrane.

Transmembrane proteins

A class of integral proteins that extend all the way across the entire phospholipid bilayer.

Peripheral proteins

Proteins bound to the inner or outer surface of the membrane that do not penetrate the hydrophobic core of the bilayer.

Glycoproteins

Membrane proteins attached to carbohydrate chains that extend into the extracellular environment and function as cell surface markers.

Glycolipids

Membrane lipids bonded to carbohydrate chains that serve as tissue-specific cell surface identity markers.

Cholesterol

A lipid molecule located in the cell membrane that influences the fluidity of the fatty acid tails.

Rough endoplasmic reticulum

An organelle studded with ribosomes that synthesizes proteins and packages them into transport vesicles.

Smooth endoplasmic reticulum

An organelle that synthesizes lipids and carries out other cellular functions.

Golgi apparatus

An organelle consisting of cisternae with cis and trans regions that modifies, sorts, and packages lipids and proteins into vesicles.

Secretory vesicles

Vesicles that fuse with the plasma membrane to release proteins or substances outside the cell.

Primary lysosome

A digestive vesicle formed by the Golgi apparatus that contains digestive enzymes before combining with target material.

Secondary lysosome

A digestive organelle formed by the fusion of a primary lysosome with a phagosome.

Phagosome

A vesicle formed around food particles or extracellular material brought into the cell via phagocytosis.

Lipid rafts

Specialized membrane domains enriched in specific lipids and proteins involved in cell signaling, adhesion, and responding to stress or toxins.

MHC proteins

Cell surface proteins responsible for immune system recognition of self and non-self cells.

Micelle

A spherical structure formed in water by amphiphilic molecules where hydrophobic tails cluster internally away from water.

Unilamellar liposome

A spherical vesicle composed of a single lipid bilayer enclosing an aqueous core.

Membrane protein functions

The primary roles played by membrane proteins, including selective transport channels, enzymes, cell surface receptors, cell surface identity markers, cell adhesion, and attachment to the cytoskeleton.