In
cell biology
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living an ...
, the cleavage furrow is the indentation of the cell's surface that begins the progression of cleavage, by which animal and some algal cells undergo
cytokinesis, the final splitting of the membrane, in the process of
cell division
Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...
. The same proteins responsible for muscle contraction,
actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ...
and
myosin
Myosins () are a Protein family, family of motor proteins (though most often protein complexes) best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are adenosine triphosphate, ATP- ...
, begin the process of forming the cleavage furrow, creating an
actomyosin ring. Other
cytoskeletal
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all Cell (biology), cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane ...
proteins and actin binding proteins are involved in the procedure.
Mechanism
Plant cells do not perform cytokinesis through this exact method but the two procedures are not totally different. Animal cells form an actin-myosin
contractile ring
In molecular biology, an actomyosin ring or contractile ring, is a prominent structure during cytokinesis. It forms perpendicular to the axis of the spindle apparatus towards the end of telophase, in which sister chromatids are identically separ ...
within the equatorial region of the
cell membrane
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...
that constricts to form the cleavage furrow. In plant cells,
Golgi vesicle secretions form a cell plate or septum on the equatorial plane of the cell wall by the action of
microtubules of the
phragmoplast.
The cleavage furrow in animal cells and the phragmoplast in plant cells are complex structures made up of microtubules and
microfilaments
Microfilaments, also called actin filaments, are protein filaments in the cytoplasm of eukaryotic cells that form part of the cytoskeleton. They are primarily composed of polymers of actin, but are modified by and interact with numerous other p ...
that aide in the final separation of the cells into two identical
daughter cells.
Cell cycle
The
cell cycle
The cell cycle, or cell-division cycle, is the sequential series of events that take place in a cell (biology), cell that causes it to divide into two daughter cells. These events include the growth of the cell, duplication of its DNA (DNA re ...
begins with
interphase when the DNA replicates, the cell grows and prepares to enter mitosis.
Mitosis
Mitosis () is a part of the cell cycle in eukaryote, eukaryotic cells in which replicated chromosomes are separated into two new Cell nucleus, nuclei. Cell division by mitosis is an equational division which gives rise to genetically identic ...
includes four phases:
prophase,
metaphase,
anaphase, and
telophase. Prophase is the initial phase when
spindle fibers appear that function to move the
chromosomes toward opposite poles. This spindle apparatus consists of microtubules, microfilaments and a complex network of various proteins. During metaphase, the chromosomes line up using the spindle apparatus in the middle of the cell along the equatorial plate. The chromosomes move to opposite poles during anaphase and remain attached to the spindle fibers by their centromeres. Animal cell cleavage furrow formation is caused by a ring of actin microfilaments called the contractile ring, which forms during early anaphase. Myosin is present in the region of the contractile ring as concentrated microfilaments and actin filaments are predominant in this region. The actin filaments here are both pre-existing and new. Cleavage is driven by these
motor proteins, actin and myosin, which are the same proteins involved with muscle contraction. During cellular cleavage, the contractile ring tightens around the
cytoplasm
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...
of the cell until the cytoplasm is pinched into two daughter cells. During the final phase of mitosis, telophase, the furrow forms an intercellular bridge using mitotic spindle fibers.
Phosphatidylethanolamine has been shown to be present during this time, which indicates that it may play a role in movement between the plasma membrane and contractile ring. The bridge is then broken and resealed to form two identical daughter cells during cytokinesis. The breakage is formed by microtubules and the resealing is negated by
calcium dependent exocytosis using Golgi vesicles.
[ In comparison, the plant cell septum and the animal cell mid-zone are analogous. Both require vesicular secretions by the Golgi apparatus for resealing and formation of the cytoskeletal network, in addition to microtubules and microfilaments for division and movement.][
]
References
*
*
*
{{refend
Cell biology