Cells: The Living Units

Flashcards covering key concepts related to cellular structure, membrane function, and cellular transport processes.

Cell Theory

The cell is the smallest unit of life; all organisms are made of one or more cells; cells arise only from other cells.

Plasma Membrane

The flexible outer boundary of a cell that separates intracellular fluid from extracellular fluid.

Cytoplasm

Intracellular fluid containing organelles, located between the plasma membrane and nucleus.

Nucleus

The control center of the cell, containing DNA.

Extracellular Materials

Substances found outside cells including extracellular fluids, cellular secretions, and extracellular matrix.

Phospholipid Bilayer

A double layer of phospholipids forming the plasma membrane, with hydrophilic heads facing outward and hydrophobic tails facing inward.

Integral Proteins

Proteins that are inserted into the membrane and span the entire membrane.

Peripheral Proteins

Proteins that are loosely attached to integral proteins or anchored to the membrane.

Transport Proteins

Proteins that allow substances to cross the membrane, including channels and carriers.

Active Transport

Movement of substances against their concentration gradient, requiring energy (ATP).

Passive Transport

Movement of substances across membranes without the use of energy; includes diffusion and osmosis.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a solution to change the shape or tone of cells by altering their internal water volume.

Erythrocytes

Red blood cells that transport gases.

Macrophages

Cells that fight disease by engulfing pathogens.