Cell Biology: Membrane Structure and Function

Cholesterol acts as a fluidity buffer in animal cell membranes, maintaining fluidity at both warm and cool temperatures by restricting or preventing the tight packing of phospholipids.

Membrane proteins are categorized into integral and peripheral proteins. Integral proteins penetrate the lipid bilayer, while peripheral proteins are loosely bound to the membrane surface.

Proteins that penetrate the hydrophobic core of the lipid bilayer. Often transmembrane, meaning spanning the entire membrane.

Proteins that are loosely bound to the surface of the membrane, often associated with integral proteins.

Membrane proteins carry out various crucial roles including transport, enzymatic activity, signal transduction, recognition ,and cell adhesion.

Membrane proteins facilitate the movement of specific substances into or out of the cell.

The plasma membrane has distinct sides: the cytoplasmic side, associated with the cytoskeleton; and the exterior side, linked to the extracellular matrix.

Integral proteins have hydrophobic regions that interact with the nonpolar tails of phospholipids, and hydrophilic regions in contact with the aqueous environment.

The ability of a cell to distinguish one type of neighboring cell from another, crucial for tissue and organ development, and immune responses.

Important for cell-cell recognition; branched oligosaccharides (short chains of sugar molecules) attached to proteins or lipids (forming glycoproteins or glycolipids).

Proteins with carbohydrate chains attached, crucial for cell-cell recognition.

Lipids with carbohydrate chains attached, also involved in cell-cell recognition.

Short chains of sugars; critical for cell-cell recognition by determining cell type.

Structures that hold adjacent cells together, like gap junctions and tight junctions.

The ability of a membrane to control what enters and leaves a cell.

Describes membrane structure as a mosaic of various components (proteins, lipids) embedded in a fluid lipid bilayer.

Examples of how variations in membrane carbohydrates determine blood type.

Proteins that span the entire lipid bilayer of a cell membrane.

The movement of molecules across a cell membrane, influenced by the molecule's characteristics and cell's need.

Hydrophobic molecules like hydrocarbons easily diffuse through the lipid bilayer without assistance.

Polar molecules need help crossing the membrane, often through transport proteins.

Transport proteins that create a hydrophilic channel for molecules to travel through.

Channel proteins specifically for water movement.

Transport proteins that bind to molecules, change shape, and move them across the membrane.

Each transport protein is designed for a particular molecule or ion, preventing incorrect transport.

The nonpolar interior of the cell membrane, which blocks polar molecules.

Water-loving molecules, not readily crossing the hydrophobic membrane.

Aquaporins dramatically increase the speed of water passing through cell membranes.

Transport proteins that bind to specific molecules to move them across the membrane. Requires energy.

Transport that doesn't use a protein carrier. Includes simple diffusion.

Molecules move from high to low concentration without energy.

Molecules move across a membrane with the help of a protein, but no energy is required.

Transport requiring energy to move molecules against their concentration gradient.

Transport across the membrane without energy input.

Difference in concentration of a substance across a space or membrane.

Membrane proteins that provide a passageway for molecules to travel through.

Channel proteins that allow the movement of water across membranes.

Process of cells using energy for various activities, including membrane transport.

Movement of molecules across a membrane without energy input, following a concentration gradient.

Molecules spreading out from high to low concentration.

Difference in concentration of a substance across a space.

Passive transport of water across a selectively permeable membrane.

Membrane that allows some molecules to pass through but not others.

Proteins in the membrane that help molecules move across. (Channels let things pass, carriers change shape.)

Ability of a solution to cause a cell to gain or lose water; affected by concentration and permeability.