Biology: Levels of Organization

Atomic Structure and Cellular Hierarchy

• Atoms are the simplest level of biological organization.
• Two or more atoms combine to form a molecule.
• Macromolecules are large, biologically important molecules found inside cells.
• Organelles are composed of macromolecules and are responsible for carrying out specific functions within the cell.
• Cells are the basic living units of life, comprising one or more organelles.
• Tissues are formed when groups of cells work together to perform specific functions.
• Organs are composed of multiple tissues that work together to perform specific functions.
• Organ systems are formed when groups of organs work together to maintain homeostasis and perform specific bodily functions.
• Organisms are composed of multiple organ systems that work together to maintain overall health and function.

Understand the hierarchical structure of living organisms, from atoms to organisms. Learn how atoms, molecules, organelles, cells, tissues, organs, and organ systems work together to form a living being.