The basic unit of life and the smallest unit of life is the cell. Tissues are comprised of many cells, and many tissues make up organs. Every organism in the world is comprised of cells.
Cells are made up of smaller individual parts known as organelles. These structures come in many varieties and help individual cells undergo metabolic processes and thrive in all different types of conditions. Proteins, fats, carbohydrates and nucleic acids make up organelles and provide them with their structures and functions. Atoms and quarks make up all of these macromolecules and can also be found in every known organism.