Cell biology

Cell biology (also called cellular biology or cytology, from the Greek kytos, "container") is an academic discipline that studies cells. This includes their physiological properties such as their structure and the organelles they contain, their environment and interactions, their life cycle, division and function (physiology) and eventual death. This is done both on a microscopic and molecular level, and cell biology researches both single-celled organisms like bacteria and specialized cells in multicellular organisms like humans.

Knowing the composition of cells and how cells work is fundamental to all of the biological sciences. Appreciating the similarities and differences between cell types is particularly important to the fields of cell and molecular biology. These fundamental similarities and differences provide a unifying theme, allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Research in cell biology is closely related to genetics, biochemistry, molecular biology and developmental biology.

Movement of proteins
Proteins are synthesized by ribosomes in the cytoplasm. This process is also known as protein biosynthesis or simply protein translation. Some proteins, such as those to be incorporated in membranes (membrane proteins), are transported into the ER during synthesis and further processed in the Golgi apparatus. From the Golgi, membrane proteins can move to the plasma membrane, to other subcellular comparments or they can be secreted from the cell. The ER and Golgi can be thought of as the "membrane protein synthesis compartment" and the "membrane protein processing compartment", respectively. There is a semi-constant flux of proteins through these compartments. ER and Golgi-resident proteins associate with other proteins but remain in their respective compartments. Other proteins "flow" through the ER and Golgi to the plasma membrane. From the plasma membrane, proteins destined to be degraded move back into intracellular compartments (lysosomes) where they are broken down to their individual amino acids.

Purification of cells and their parts
Purification of cells and their parts is achieved in the following ways:
 * Cell fractionation
 * Flow cytometry
 * Release of cellular organelles by disruption of cells.
 * Separation of different organelles by centrifugation.
 * Proteins extracted from membranes by detergents and salts or other kinds of chemicals.