Membrane Transport and Cell Signaling

These flashcards cover key vocabulary and concepts related to membrane transport and cell signaling as presented in lecture notes, focusing on the structure, functions, processes, and roles of the plasma membrane.

Fluid Mosaic Model

A model describing the structure of cell membranes, where lipids and proteins are embedded in a fluid bilayer.

Selective permeability

The ability of a cell membrane to allow certain substances to pass through while blocking others.

Passive transport

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

Active transport

The movement of substances against their concentration gradient, requiring energy, typically from ATP.

Exocytosis

The process by which a cell expels materials in vesicles that fuse with the plasma membrane.

Endocytosis

The process by which a cell takes in materials by engulfing them in a vesicle formed from the plasma membrane.

Aquaporins

Channel proteins in the plasma membrane that facilitate the rapid transport of water molecules.

Signal transduction

The process by which a cell converts an external signal into a functional response.

Cell signaling

The communication that occurs between cells, allowing them to coordinate their functions.

Receptor proteins

Proteins that bind specific signaling molecules, initiating a cellular response.

Cotransport

A mechanism where movement of one substance across a membrane drives the movement of another substance.

Phosphorylation cascade

A sequence of events where one enzyme activates another through phosphorylation, amplifying the signal.

Second messengers

Small molecules that participate in intracellular signaling, commonly including cyclic AMP.

Transmembrane proteins

Proteins that span the lipid bilayer, often involved in transport across cell membranes.

G protein-coupled receptors (GPCRs)

A large family of receptors that sense molecules outside the cell and activate internal signal transduction pathways.

Ligand-gated ion channels

Receptor proteins that open or close in response to the binding of signaling molecules, regulating ion flow.

Endosymbiont theory

The hypothesis that certain organelles, like mitochondria, originated from prokaryotic cells that were engulfed by ancestral eukaryotic cells.

Emergent properties

New attributes that arise at a level of organization that are not present in the individual components.

Bulk transport

The movement of large quantities of materials into or out of cells, typically via vesicles.

Mitochondria

Organelles that produce ATP through cellular respiration, playing a critical role in energy metabolism.

Chloroplasts

Organelles in plant cells that conduct photosynthesis, converting light energy into chemical energy.