Chapter 4

Journey into the Cell

How do cells utilize the energy provided by the glucose? What internal structures in cells need energy to function and what internal structures make the cell capable of using the glucose?

Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

All organisms are composed of cells - the fundamental unit of life. Most organisms are single cells; other organisms, including humans, are multicellular.

Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs.

Cells carry on the many functions needed to sustain life. They grow and divide, thereby producing more cells. This requires that they take in nutrients, which they use to provide energy for the work that cells do and to make the materials that a cell or an organism needs.