Cell
biology (also called cellular biology or formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and
molecular level.
Cell biology research extends to both the great diversity of single-celled organisms like bacteria and the many 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 also 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.ProcessesMovement of proteinsEach type of protein
is usually sent to a particular part of the cell. An important part of
cell biology is the investigation of molecular mechanisms by which
proteins are moved to different places inside cells or secreted from
cells.
Most 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 or endoplasmic reticulum during synthesis and further processed in the Golgi apparatus. From the Golgi, membrane proteins can move to the plasma membrane,
to other subcellular
compartments 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. Motor proteins transport membrane protein-containing vesicles along cytoskeletal tracks to distant parts of cells such as axon terminals.
Some proteins that are made in the cytoplasm contain structural features that target them for transport into mitochondria or the nucleus. Some mitochondrial proteins are made inside mitochondria and are coded for by mitochondrial DNA. In plants, chloroplasts also make some cell proteins.
Extracellular and cell surface proteins destined to be degraded can
move back into intracellular compartments upon being incorporated into endocytosed vesicles. Some of these vesicles fuse with lysosomes where the proteins are broken down to their individual amino acids. The degradation of some membrane proteins begins while still at the cell surface when they are cleaved by secretases. Proteins that function in the cytoplasm are often degraded by proteasomes.
More abstracts about the cell biology of paul_william