The Architecture of Life: Exploring Plant and Animal Cells

Every living organism on Earth, from the towering redwood trees in coastal forests to the microscopic bacteria in a drop of pond water, shares a fundamental characteristic: they are all constructed from cells. Often referred to as the building blocks of life, cells are the smallest structural and functional units capable of performing all the necessary tasks to sustain life. In complex multicellular organisms such as plants and animals, trillions of specialized cells work in concert to build complex systems, maintain internal stability, and allow organisms to grow and reproduce.

To understand how cells function, it is helpful to examine what they are made of at the chemical and physical level. At the most basic level, a cell is composed of water, minerals, and four vital classes of biological macromolecules: carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates provide readily available energy, lipids form structural boundaries and store long-term energy, proteins perform diverse cellular tasks such as building tissues and facilitating chemical reactions, and nucleic acids like DNA and RNA hold the genetic instructions for all cellular activity. Within this chemical environment sits the cytoplasm, a gel-like fluid that fills the interior of the cell, providing a medium in which cellular components can move and chemical reactions can take place.