From What Are Cells Made?

Cells contain a variety of components, including water, proteins, lipids and carbohydrates. Regardless of type, cells contain approximately two-thirds water. Their remaining inner core forms from a combination of molecules, which cells use to help the body carry out basic and important tasks like processing food and delivering energy to different parts of the system.

Cells rely on water and molecules to help process and break down food and perform chemical reactions. They transform basic raw materials into usable energy and chemical compounds.

The role of cells varies with their location in the body. Cells in the digestive system work primarily to break down and deliver food, while those in the brain deliver chemical and electrical signals. Within the materials forming cells lie many different types and varieties. Cells contain hundreds of proteins alone, which help cells carry out vital functions in different ways.

Proteins appear in every part of cells and help with all cellular activities. Some give cells shape and structure, while others regulate the flow of materials and components inside and outside of the cell walls. Other proteins serve as mechanics, making repairs to cells after damage. Proteins also help with cell division, which is essential for cell growth and reproduction. Common proteins include microtubules, centrioles and histones.