The fundamental concept of biology that states that all living things are composed of cells; that cells are the basic units of structure and function in living things; and that new cells are produced from existing cells. 

In cells, the structure that contains the cell’s genetic material in the form of DNA.

An organism whose cells contain a nucleus. 

A unicellular organism that lacks a nucleus. 

In eukaryotic cells, all cellular contents outside the nucleus; in prokaryotic cells, all of the cells’ contents. 

A specialized structure that performs important cellular functions within a cell. 

A cell organelle that stores materials such as water, salts, proteins, and carbohydrates.

A cell organelle that breaks down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell. 

A network of protein filaments in a eukaryotic cell that gives the cell its shape and internal organization and is involved in movement. 

A cell organelle consisting of RNA and protein found throughout the cytoplasm in a cell; the site of protein synthesis. 

The internal membrane system found in eukaryotic cells; the place where lipid components of the cell membrane are assembled. 

An organelle in cells that modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell. 

An organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy. 

A cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use. 

A flexible double-layered sheet that makes up the cell membrane and forms a barrier between the cell and its surroundings. 

The process by which particles tend to move from an area where they are more concentrated to an area where they are less concentrated. 

The process of diffusion in which molecules pass across the membrane through cell membrane channels. 

Diffusion of water through a selectively permeable membrane. 

Pressure that must be applied to prevent osmotic movement across a selectively permeable membrane. 

Relatively constant internal physical and chemical conditions that organisms maintain. 

A group of similar cells that perform a particular function. 

A group of tissues that work together to perform closely related functions. 

A group of organs that work together to perform a specific function.

A type of active transport in which the membrane forms a pocket around a particle outside the cell. The pocket pinches close on the inside of the cell, forming a vesicle. The vesicle breaks loose, bringing the particle into the cell. 

A type of active transport in which the vesicle inside the cell carries a particle to the cell membrane. The membrane of the vesicle sticks to and becomes part of the cell membrane. The particle is forced out of the cell. 

An effect of osmosis where the concentration is the same inside and outside the cell. Water molecules move at the same rate in both directions. 

An effect of osmosis where the outside solution has a higher concentration than the solution inside the cell. Movement of water molecules out of the cell causes it to shrink. 

An effect of osmosis where the outside solution has a lower concentration than the solution inside the cell. Movement of water molecules into the cell causes it to swell. 

A thin, flexible barrier that surrounds all cells; regulates what enters and leaves the cell.