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Cell

The basic, living, structural, and functional unit of the body.

Cytology

The study of cell structure and function.

Plasma Membrane

A flexible, sturdy barrier that surrounds and contains the cytoplasm of the cell.

Fluid Mosaic Model

Describes the structure of the plasma membrane, consisting of proteins in a sea of lipids.

Lipid Bilayer

The basic framework of the plasma membrane consisting of phospholipids, cholesterol, and glycolipids.

Amphipathic Molecules

Molecules that have both polar (charged) and nonpolar (uncharged) parts.

Integral Proteins

Membrane proteins that extend into or across the lipid bilayer.

Peripheral Proteins

Proteins found at the inner or outer surface of the membrane; can be removed without disturbing the membrane.

Glycocalyx

The combined glycoproteins and glycolipids that help cells recognize and adhere to one another.

Ion Channels

Proteins that allow ions to pass through the plasma membrane.

Selective Permeability

A property of plasma membranes that allows some substances to pass through while others cannot.

Concentration Gradient

The difference in the concentration of a chemical between one side of the plasma membrane and the other.

Mitosis

Nuclear division that results in the duplication of body cells.

Meiosis

Nuclear division that results in the production of sperm and eggs.

Passive Transport

Movement of substances across the membrane that does not require energy.

Active Transport

Movement of substances against their concentration gradient that requires energy.

Diffusion

The random mixing of particles in a solution driven by their kinetic energy.

Facilitated Diffusion

A passive transport process assisted by integral membrane proteins for polar or charged solutes.

Osmosis

The net movement of water through a selectively permeable membrane.

Tonicity

How a solution influences the shape of body cells.

Primary Active Transport

A process that uses ATP to pump substances across the plasma membrane against their concentration gradient.

Secondary Active Transport

Uses the energy from a concentration gradient to move other substances against their own gradient.

Endocytosis

Process by which materials move into a cell in a vesicle formed from the plasma membrane.

Phagocytosis

The ingestion of solid particles by certain cells.

Pinocytosis

The ingestion of extracellular fluid by a cell.

Exocytosis

Process where membrane-enclosed structures release their contents into the extracellular fluid.

Cytosol

The semifluid portion of cytoplasm that contains inclusions and dissolved solutes.

Cytoskeleton

A network of protein filaments that provides structural support for the cell.

Organelles

Specialized structures within a cell that perform specific functions for growth and reproduction.

Mitochondria

Organelles that are the site of ATP production in cells.

Nucleus

The membrane-bound organelle that contains DNA and controls cellular activities.

Ribosomes

Structures responsible for protein synthesis, consisting of ribosomal RNA and proteins.

Clinical Connection: Cancer

A group of diseases characterized by uncontrolled cell proliferation.

Carcinogenesis

The multistep process by which normal cells acquire mutations that lead to cancer.

Apoptosis

Programmed cell death.

Necrosis

Pathological cell death due to injury.

Genomics

The study of the genome and its relationship to body function.

Tumor-Suppressor Genes

Genes that produce proteins that inhibit cell division and may prevent cancer.

Recombinant DNA

Techniques used to manipulate DNA for genetic engineering.