Chapter 5: Structure and Function of Plasma Membranes

These flashcards cover key terms and concepts related to the structure and function of plasma membranes, including their components, processes, and properties.

Plasma Membrane

A selective barrier that encloses all cells, with functions including regulating entry and exit of substances and communication between cells.

Fluid-Mosaic Model

Describes the plasma membrane structure as a fluid phospholipid bilayer with various proteins and molecules embedded, making it a dynamic and complex structure.

Selective Permeability

The property of the plasma membrane that allows some substances to pass through while preventing others from doing so.

Osmosis

The diffusion of water across a semi-permeable membrane, driven by the concentration gradients of solute particles.

Endocytosis

The process by which the plasma membrane engulfs molecules to bring them into the cell, forming a vesicle.

Exocytosis

The process of transporting molecules out of the cell via vesicles that fuse with the plasma membrane.

Hydrophilic

Substances that are water-attracting or water-soluble, typically found in the 'heads' of phospholipid molecules.

Hydrophobic

Substances that repel water, usually associated with the 'tails' of phospholipid molecules sequestered in the membrane.

Glycoproteins

Proteins with sugar molecules attached that play roles in cell recognition and adhesion.

Diffusion

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

Active Transport

The process that requires energy (ATP) to move substances against their concentration gradient.

Fluidity

The characteristic of a membrane that allows the components to move laterally within the layer, contributing to its flexibility.

Tonicity

The relative concentration of solutes in solutions, affecting the movement of water and the shape of cells.

Permeability

The ability of the plasma membrane to allow substances to pass through it, influenced by its structure.

Cell Wall

A rigid layer found in plant, fungi, and bacterial cells that provides support but does not regulate transport.