Chapter 4: Membranes and Signalling

These flashcards cover key concepts from Chapter 4 regarding the structure and function of membranes, signaling mechanisms, and transport processes.

Fluid Mosaic Model

A model that describes the structure of cell membranes as a mosaic of various proteins that float in or on a fluid lipid bilayer.

Membrane Asymmetry

The phenomenon where the two halves of a membrane bilayer have different compositions and properties.

Passive Transport

The movement of substances across a membrane without the need for energy input.

Facilitated Diffusion

A type of passive transport that relies on transport proteins to help move molecules across the membrane.

Osmosis

The passive diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water, based on solute concentration.

Active Transport

The movement of ions or molecules across a cell membrane against their concentration gradient, requiring energy.

Primary Active Transport

A type of active transport where the energy derived from ATP hydrolysis is used directly to transport substances.

Secondary Active Transport

A type of active transport that does not use ATP directly but relies on the gradient created by primary active transport.

Signal Transduction

The process by which a chemical or physical signal is transmitted through a cell as a series of molecular events.

Receptor-Mediated Endocytosis

A process by which cells absorb metabolites, hormones, other proteins – and in some cases, viruses – by the inward budding of the plasma membrane.

Protein Kinases

Enzymes that transfer phosphate groups from ATP to specific target proteins, stimulating or inhibiting their activity.

Desaturases

Enzymes that introduce double bonds into fatty acid chains, affecting membrane fluidity.

Channel Proteins

Proteins that span the membrane and allow specific ions or water to cross the membrane at rates much higher than by simple diffusion.

Carrier Proteins

Proteins that bind to specific molecules and change shape to shuttle them across the membrane.

Fluidity of Lipid Bilayer

The ability of lipids within the bilayer to move and rearrange, influenced by temperature and lipid composition.

Endocytosis

The process by which cells take in materials from their environment by engulfing them in a vesicle.