Chapter_5_Plasma_Membrane__1_

Plasma membrane

A barrier that separates the interior of a cell from its external environment, controlling the passage of substances in and out.

Selectively permeability

The ability of a membrane to allow certain molecules to pass through while restricting others.

Phospholipid

A type of lipid molecule that is a main component of cell membranes, consisting of hydrophilic and hydrophobic parts.

Amphipathic

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

Integral proteins

Membrane proteins that are permanently attached to the biological membrane and play roles in transport and communication.

Peripheral proteins

Membrane proteins that are temporarily attached to the lipid bilayer or to integral proteins, often involved in signaling.

Glycoproteins

Proteins that have carbohydrate groups attached to them, important for cell recognition and signaling.

Glycolipids

Lipids with carbohydrate attached, contributing to the maintenance of the cell membrane structure and recognition.

Endomembrane system

A series of membranes within a cell, which include the nuclear envelope, endoplasmic reticulum, Golgi apparatus, and vesicles.

Passive transport

The movement of substances across a cell membrane without the use of energy by the cell.

Active transport

The movement of substances against their concentration gradient, requiring energy, often in the form of ATP.

Diffusion

The process by which molecules spread from an area of high concentration to an area of low concentration.

Facilitated diffusion

The process of passive transport of molecules across a membrane via a protein carrier.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a solution to cause a cell to gain or lose water.

Electrochemical gradient

The combined difference in concentration and charge across a membrane that affects the movement of ions.

Sodium-potassium pump

An active transport mechanism that moves sodium out of the cell and potassium into the cell, essential for maintaining cellular homeostasis.

Secondary active transport

A type of transport in which energy from an electrochemical gradient (established by primary active transport) is used to move other substances against their gradient.

Endocytosis

The process by which cells internalize substances from their external environment by engulfing them in a vesicle.

Exocytosis

The process by which cells expel large amounts of material through vesicles that fuse with the membrane.

Phagocytosis

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

Pinocytosis

A type of endocytosis where the cell ingests fluid along with small solutes.

Receptor-mediated endocytosis

A more selective form of endocytosis where cells internalize molecules based on the presence of specific receptors.