Cytology

Cytology is the study of the cells, especially their appearance and structure. Cells are the small parts that make up all living things, and their effects on each other and their environment.

There are two types of cells. Prokaryotic cells do not have a clear and easy-to-see nucleus, and do not have a membrane, or wall, around them. Eukaryotic cells have an easy-to-see nucleus where all of the cell's functions take place, and a membrane around them. The main organelles of a cell and their uses are:

• Mitochondria: produces energy for the cell
• Endoplasmic reticulum: makes proteins and carbohydrates for the cell to use
• Golgi bodies: store and package products that the cell uses
• Plastid (present in plant cells only): contains chemicals needed to photosynthesize (create energy from sunlight); in plants only.
• Nucleus: directs the actions of the cell
• Centrosomes: guides the cell in mitosis and meiosis, the processes for cell division.