Week 3: Cell Membrane and their Functions

Plasma Membrane

The barrier protecting the cell's inner content from the extracellular environment, allowing selective permeability.

Facilitated Diffusion

A passive transport process requiring a carrier protein to move substances like glucose down their concentration gradient.

Transmembrane Proteins

Integral proteins that span the bilayer and are permanently attached to the plasma membrane.

Fluid Mosaic Model

A model describing the plasma membrane as a mosaic of various components that move fluidly.

Selective Permeability

The property of the plasma membrane that allows only certain molecules to enter or exit the cell.

Endocytosis

The cellular mechanism of internalizing extracellular substances by enclosing them in a vesicle.

Osmosis

The diffusion of water across a selectively permeable membrane, from an area of higher water concentration to lower.

Active Transport

The process of moving molecules against their concentration gradient using energy from ATP.

Sodium-Potassium Pump

A primary active transport mechanism that maintains the electrochemical gradient of sodium and potassium ions.

Peripheral Proteins

Proteins attached to one layer of the membrane that perform functions such as cell signaling.

Carbohydrates in Cell Membranes

Sugars attached to proteins or lipids that provide protection and help in cell-cell recognition.

Hypertonic Solution

A solution with a higher concentration of solutes compared to the intracellular fluid, causing water to exit cells and leading to cell shrinkage.

Hypotonic Solution

A solution with a lower concentration of solutes compared to the intracellular fluid, leading to water entering cells and potential cell lysis.

Ion Channels

Integral proteins that allow specific ions to cross the plasma membrane.

Receptor Proteins

Membrane proteins that bind to specific molecules, known as ligands, triggering changes in cellular activity.

Passive Transport

The movement of substances down their concentration gradient without the use of cellular energy.

Glycolipids

Lipids with carbohydrate segments that participate in cell-cell interactions.

Cholesterol in Membrane

An amphipathic lipid that decreases membrane fluidity and provides stiffness.

Na+/K+ ATPase

A transmembrane pump that moves sodium out of and potassium into the cell, maintaining concentration gradients.

Endocytosis vs Exocytosis

Endocytosis is the process of taking substances into the cell, while exocytosis is the process of expelling materials from the cell.

Dynamic Equilibrium

A state achieved when concentrations of substances are equal on both sides of the membrane.