Chapter Review: Membrane Functions and Structure

Flashcards covering membrane proteins, cell interactions, the fluid mosaic model, membrane asymmetry, and permeability based on lecture notes.

Transmembrane protein functions

Can act as enzymes (e.g., receptor tyrosine kinase), be involved in cell signaling, and facilitate cell-cell recognition.

Receptor tyrosine kinase

A type of enzyme found as a transmembrane protein, involved in cell signaling.

Cell signaling

The process by which cells respond to internal or external stimuli, enabling them to know their environment or interact with other cells.

Cell-cell recognition

The ability of cells to distinguish and interact with other cells, often involving the binding of proteins (e.g., virus infection mechanisms).

Intercellular joining

Physical connections between cells, such as tight junctions, desmosomes, and gap junctions, facilitated by transmembrane proteins.

Tight junction

A type of intercellular connection that acts like a zipper, joining two cells closely along their entire contact area.

Desmosome

A type of intercellular connection forming disc-like attachments, acting like staples between cells.

Gap junction

A type of intercellular connection forming tunnels that allow cytosol to pass directly between cells.

Fluid mosaic model

A model describing the cell membrane as a dynamic structure composed of a fluid lipid bilayer with proteins embedded in a mosaic pattern, allowing for movement and various functions.

Membrane fluidity

The lateral movement of lipids and proteins within the cell membrane, influenced by the saturation of fatty acids.

Membrane asymmetry

The property of cell membranes having different sides, where the outer and inner faces are distinct due to facing different environments.

Lumen of organelles

The internal space within organelles, which is continuous with the extracellular space through the process of vesicle fusion with the plasma membrane.

Selectively permeable membrane

A membrane that allows certain substances to pass through more easily than others, controlling entry and exit of molecules.

Semi-permeable membrane

A membrane through which some substances can diffuse freely without the cell's control, based on their size and polarity.

Permeability factors

The properties of molecules that determine their ability to pass through a membrane, primarily size and polarity.

Hydrophobic molecules (membrane permeability)

Molecules that are highly permeable to the membrane, diffusing easily across due to the membrane's hydrophobic interior, regardless of size.

Polar molecules (membrane permeability)

Molecules with low permeability to the membrane; small ones like water can pass, but larger ones like glucose cannot easily.

Charged ions/molecules (membrane permeability)

Molecules that are impermeable to the membrane and cannot pass through it directly.

Osmosis

The diffusion of water through a semi-permeable membrane.