All living things are made up of cells. Some organisms, such as bacteria, may exist solely as single-celled creatures. Others, including humans, are comprised of countless cells all working together to form a single living being. Humans are comprised of trillions of cells that are organized into tissues such as muscle and skin or organs like the liver or lung. The animation below depicts the relationship between an organ (the liver) and the cells from which it is constructed. The final image is a close-up view of a single cell.

The proper function of human bodies is dependent on smaller structures, or organs, such as the heart or lungs. The tiny cells that make up these organs actually contain within them smaller structures called organelles. These organelles help the cells to perform their jobs. In cancer, changes to these organelles can cause the individual cells and ultimately the entire organism to have serious problems. To get a better understanding of how cells work, we will now spend some time examining some of these subcellular structures.

The organelles that we will discuss are involved in the information flow within cells and in energy production. In addition, we will look at a structure that gives cells their shape and allows them to reproduce themselves. All of the organelles and processes to be discussed have direct relevance to cancer because these are the cellular structures/activities that become disturbed in the disease.

The image below shows two living mouse cells. The mitochondria are colored red and the nuclei (with brightly stained chromosomes) are colored blue. The green colored region near the nuclei of the cells represents the golgi apparatus, anorganelle involved in the processing and packaging of molecules within the cell.

Stained Cells

The image above was used with the permission of the copyright owner, Molecular Probes.

The organelles responsible for maintaining proper cellular function are described in the following sections:

  • Nucleus
  • Mitochondria
  • Ribosome
  • Cytoskeleton
  • Interactive Game: Know the Flow
  • Cell Structure Summary Sheet