Cellular structure refers to the organization and arrangement of cells, which are the basic building blocks of all living organisms. Each cell is surrounded by a protective membrane and contains various components, such as the nucleus, which houses genetic material, and organelles like mitochondria that produce energy. These structures work together to perform essential functions, allowing the organism to grow, reproduce, and respond to its environment. In multicellular organisms, cells can specialize to perform specific tasks, forming tissues and organs. For example, muscle cells are designed for movement, while nerve cells transmit signals throughout the body. This specialization is crucial for the overall functioning and efficiency of complex life forms.