BIO140 Lecture Flashcards: Cells, Membranes, and Homeostasis

Lipid Bilayer

A double-layered sheet that forms the core of nearly all cell membranes, composed of phospholipids.

Hydrophobic

Pertaining to molecules or parts of molecules that do not interact well with water; typically nonpolar.

Hydrophilic

Referring to molecules or parts of molecules that interact well with water; typically polar.

Cell Theory

The theory that states all organisms are composed of cells, cells are the basic unit of life, and all cells come from existing cells.

Fluid-Mosaic Model

A model that describes the structure of cell membranes as a mosaic of various components including lipids, proteins, and carbohydrates, which are in constant motion.

Passive Transport

The movement of substances across a cell membrane without the need for energy input, typically occurring along a concentration gradient.

Osmosis

The diffusion of water across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration.

Aquaporins

Channel proteins that facilitate the rapid transport of water across a cell membrane.

Turgor Pressure

The pressure exerted by the fluid (usually water) inside a plant cell against the cell wall, important for maintaining cell shape.

Integral Membrane Proteins

Proteins that are permanently attached to the membrane and may span across the lipid bilayer.

Peripheral Membrane Proteins

Proteins that are temporarily associated with the membrane through weak interactions and do not penetrate the lipid bilayer.

Van der Waals Forces

Weak attractions between molecules due to transient shifts in electron density, important for stabilizing membranes.

Saturated Fatty Acids