Cell Movement

Plasma membrane

A selectively permeable barrier that allows certain substances to cross more easily than others.

Fluid mosaic model

Describes the structure of the plasma membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer of phospholipids.

Amphipathic

Molecules that have both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions.

Lateral movement

The ability of phospholipids and proteins to move sideways within the membrane, contributing to its fluidity.

Cholesterol's role in cell membranes

Helps maintain the fluidity of the membrane, preventing it from becoming too rigid.

Peripheral proteins

Proteins that are bound to the surface of the membrane.

Integral proteins

Proteins that are embedded in the membrane and can span the entire lipid bilayer.

Diffusion

The tendency of a substance to spread out in an open area, moving from an area of high concentration to low concentration.

Facilitated diffusion

The process of diffusion of molecules across a membrane via transport proteins that assist movement.

Aquaporins

Transport proteins that facilitate the movement of water across cell membranes.

Osmosis

The movement of water across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.

Hypertonic solution

A solution with a higher concentration of solutes compared to another solution.

Hypotonic solution

A solution with a lower concentration of solutes compared to another solution.

Isotonic solution

A solution where the concentration of solutes is equal to that in another solution.

Plasmolysis

The process in which the plasma membrane pulls away from the cell wall due to water loss.

Active transport

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

Sodium-potassium pump

An active transport mechanism that moves 3 sodium ions out of the cell and 2 potassium ions into the cell using energy from ATP.

Membrane potential

The voltage difference across a cell's plasma membrane, essential for the function of cells.

Exocytosis

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

Endocytosis

The process by which cells take in materials by engulfing them in vesicles formed from the plasma membrane.

Phagocytosis

A type of endocytosis where a cell engulfs large particles or cells by extending pseudopodia.

Pinocytosis

A type of endocytosis in which a cell engulfs droplets of extracellular fluid.

Receptor-mediated endocytosis

A type of endocytosis that involves the binding of extracellular substances to specific receptors, triggering vesicle formation.