Biological Organization: Levels of Life

Abiotic Levels of Organization

Subatomic Level

Composed of different particles (protons, neutrons, and electrons) that form atoms.

Atomic Level

Consists of atoms of the chemical elements from which living matter is formed. The different types of atoms are represented in the periodic table according to their number of protons within their nucleus. For example:

• Nitrogen
• Carbon
• Hydrogen
• Oxygen
• Phosphorus
• Sulfur

Molecular Level

Molecules are formed by the joining of two or more atoms. This level includes both inorganic and organic molecules.

Inorganic Molecules

• Water
• Gases
• Mineral salts

Organic Molecules

• Simple sugars
• Lipids
• Nucleotides
• Amino acids

Macromolecular Level

Macromolecules are formed when molecules join together. For example, proteins are formed when amino acid molecules come together; complex sugars are formed from simple sugars; and nucleic acids are composed of many nucleotides.

Examples of Macromolecules

• Proteins
• Complex sugars
• Nucleic acids

Building Blocks for Macromolecules

• Many amino acids
• Many simple sugars
• Many nucleotides

Organelle Level

When macromolecules join together to form organelles such as mitochondria and cell structures like the cell membrane.

Biotic Levels of Organization

Cellular Level

Organelles can be considered as the organs of cells. They come together to form cells, which are the basic structural unit of living things. Examples of cells are muscle cells or bone cells.

Multicellular Level

Organisms that contain more than one cell are classified into this level. These organisms exhibit increasing complexity, leading to further sublevels of organization based on specialized functions and structures.

Tissue Sublevel

Cells with the same origin which contribute to a specific function form a tissue. For example, muscle tissue and bone tissue.

Organ Sublevel

Organs are formed from different types of tissue that work together to perform a specific function. For example, the heart and a bone.

Organ System Sublevel

Organ system sublevels are made up.