Lipids, Membranes, and the First Cells

This set of flashcards covers key vocabulary and concepts related to lipids, membranes, and cellular transport mechanisms.

Lipid

A group of biological molecules that include fats, oils, waxes, phospholipids, and steroids.

Hydrophilic

Having an affinity for water; water-loving.

Hydrophobic

Repelling water; not having an affinity for water.

Phospholipid

A lipid composed of a hydrophilic head and two hydrophobic tails; a major component of cell membranes.

Saturated fatty acid

A fatty acid in which all carbon atoms are connected by single bonds and contains the maximum number of hydrogen atoms.

Unsaturated fatty acid

A fatty acid that contains one or more double bonds between carbon atoms, resulting in fewer hydrogen atoms.

Steroid

A type of lipid characterized by a carbon skeleton with four fused rings; includes hormones like estrogen and testosterone.

Micelle

A spherical arrangement of molecules with hydrophilic heads facing outward and hydrophobic tails inwards.

Liposome

A spherical vesicle composed of a lipid bilayer, used in drug delivery.

Osmosis

The diffusion of water across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Diffusion

The passive movement of molecules from an area of higher concentration to an area of lower concentration.

Active transport

The movement of molecules across a membrane using energy, against their concentration gradient.

Endocytosis

The process by which cells internalize substances (e.g., fluids, particles) by engulfing them.

Exocytosis

The process of expelling materials from the cell via vesicles.

CFTR

Cystic Fibrosis Transmembrane Conductance Regulator, a protein that functions as a chloride channel in epithelial cells.

Aquaporin

A channel protein that facilitates the transport of water across cell membranes.

Ion channel

A protein structure that allows ions to pass through the membrane in response to changes in membrane potential.

Carrier protein

A protein that transports substances across a cell membrane through a series of conformational changes.

Amphipathic protein

A protein that contains both hydrophilic and hydrophobic regions, allowing it to interact with both the lipid bilayer and the aqueous environment.

Fluid mosaic model

A model of cell membrane structure depicting it as a mosaic of components including phospholipids, proteins, cholesterol, and carbohydrates that move fluidly.

Biosynthesis

The process by which living organisms produce complex molecules from simpler ones, typically involving enzymatic activity.