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Totipotency
 
 
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Totipotency is the ability of a single cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
 to divide and produce all the differentiated cells in an organism
Organism

In biology, an organism is any life thing . In at least some form, all organisms are capable of response to stimulus , reproduction, growth and developmental biology, and maintenance of homeostasis as a stable whole....
, including extraembryonic tissues. Totipotent cells formed during sexual and asexual reproduction include spore
Spore

In biology, a spore is a reproduction structure that is adapted for biological dispersal and surviving for extended periods of time in unfavorable conditions....
s and zygote
Zygote

A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
s. Zygotes are the products of the fusion of two gamete
Gamete

A gamete is a Cell that fuses with another gamete during fertilization in organisms that sexual reproduction. In species which produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual which produces the larger type of gamete?called an ovum ?and a male produces th...
s (fertilization). In some organisms, cells can dedifferentiate and regain totipotency. For example, a plant cutting or callus
Callus (cell biology)

In biological research and biotechnology, a callus of cells is a mass of undifferentiated cells. In plant biology, callus cells are those cells that cover a plant wound....
 can be used to grow an entire plant.

Human development begins when a sperm
Spermatozoon

A sperm, from the ancient Greek word sp???a and and more commonly known as a sperm cell, is the ploidy cell that is the male gamete. It Fertilization an ovum to form a zygote....
 fertilizes an egg and creates a single totipotent cell (zygote).






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Encyclopedia


Totipotency is the ability of a single cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
 to divide and produce all the differentiated cells in an organism
Organism

In biology, an organism is any life thing . In at least some form, all organisms are capable of response to stimulus , reproduction, growth and developmental biology, and maintenance of homeostasis as a stable whole....
, including extraembryonic tissues. Totipotent cells formed during sexual and asexual reproduction include spore
Spore

In biology, a spore is a reproduction structure that is adapted for biological dispersal and surviving for extended periods of time in unfavorable conditions....
s and zygote
Zygote

A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
s. Zygotes are the products of the fusion of two gamete
Gamete

A gamete is a Cell that fuses with another gamete during fertilization in organisms that sexual reproduction. In species which produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual which produces the larger type of gamete?called an ovum ?and a male produces th...
s (fertilization). In some organisms, cells can dedifferentiate and regain totipotency. For example, a plant cutting or callus
Callus (cell biology)

In biological research and biotechnology, a callus of cells is a mass of undifferentiated cells. In plant biology, callus cells are those cells that cover a plant wound....
 can be used to grow an entire plant.

Human development begins when a sperm
Spermatozoon

A sperm, from the ancient Greek word sp???a and and more commonly known as a sperm cell, is the ploidy cell that is the male gamete. It Fertilization an ovum to form a zygote....
 fertilizes an egg and creates a single totipotent cell (zygote). In the first hours after fertilization, this cell divides into identical totipotent cells. Approximately four days after fertilization and after several cycles of cell division, these totipotent cells begin to specialize.

Totipotent cells have total potential. They can specialize into pluripotent cells that can give rise to most, but not all, of the tissues necessary for fetal development. Pluripotent cells undergo further specialization into multipotent cells that are committed to give rise to cells that have a particular function. For example, multipotent blood stem cells give rise to the red cells
Red blood cell

Red blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen to the body tissues via the blood....
, white cells
White blood cell

White blood cells , or leukocytes , are cell of the immune system defending the body against both infectious disease and foreign materials....
 and platelet
Platelet

Platelets, or Thrombocyte, are small, irregularly shaped anuclear cells, 2-4?m in diameter, which are derived from fragmentation of precursor megakaryocytes....
s in the blood.

Importantly, totipotent cells must be able to differentiate not only into any cell in the organism, but also into the extraembryonic tissue associated with that organism. For example, human stem cells are considered totipotent only if they can develop into any cell in the body, or into placenta
Placenta

The placenta or afterbirth is a highly vascularized ephemeral organ present in Placentalia vertebrates that connects the developing fetal tissues to the uterine wall....
l cells that do not become part of the developing fetus. This fact is an important aspect of the stem cell controversy
Stem cell controversy

Stem cell controversy is the ethical debate centered on research involving the creation, usage and destruction of human embryonic stem cells. Not all stem cell research involves the creation, usage and destruction of human embryos....
 because the human embryonic stem cells used for research purposes are pluripotent; they are collected from human embryos that have developed past the totipotent cell stage.

Basis of totipotency

The molecular mechanisms controlling totipotency are not well understood and are a subject for current research. In particular, a suggests that in the model organism Caenorhabditis elegans
Caenorhabditis elegans

'Caenorhabditis elegans' is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular biology and developmental biology of C....
, multiple mechanisms including RNA regulation maintain totipotency at different stages of development.

See also

  • Stem cell
    Stem cell

    Stem cells are Cell found in most, if not all, multi-cellular organisms. They are characterized by the ability to renew themselves through Mitosis cell division and Cellular differentiation into a diverse range of specialized cell types....
  • Zygote
    Zygote

    A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
  • Spore
    Spore

    In biology, a spore is a reproduction structure that is adapted for biological dispersal and surviving for extended periods of time in unfavorable conditions....
  • Pluripotent