All cells come from preexisting cells. a cell divides its dna in a process known as and its cytoplasmic contents in a process known as , producing two new daughter cells while all life begins as a single cell, the human body is not just one cell type. cells that can divide without becoming a specific cell type (i. e. skin cells) are known as . when stem cells undergo mitosis and divide, they produce two cells. one cell remains a stem cell and the other is a partially specialized cell known as a cell. cells undergo a process of specialization or determination called to become neurons, muscle cells, or skin cells. stem cells are the source of all different cell types.

All cells come from preexisting cells. a cell divides its DNA in a process known as mitosis and its cytoplasmic contents in a process known as cytokinesis, producing two new daughter cells. The cell division enables tissues to form, grow and repair.

While all life begins as a single cell, the human body is not just one cell type. cells that can divide without becoming a specific cell type (i.e. skin cells) are known as stem cells or totipotent cells. These stem cells can become any type of cell.

When stem cells undergo mitosis and divide, they produce two cells. one cell remains a stem cell and the other is a partially specialized cell known as a progenitor cell. The progenitor cells become more and more specialized and eventually form specialized cells.

 Cells undergo a process of specialization or determination called differentiation to become neurons, muscle cells, or skin cells. stem cells are the source of all different cell types. Since all cells have the same DNA, epigenetic changes and the involvement of transcript factors are necessary to differentiate a stem cell into a specialized cell.

Mantle convection  is the slow  creepingmotion of earth's solid silicate  mantle  caused by  convection  currents carrying  heat from the interior  to the planet's surface.[1][2]  the earth's surface  lithosphere, which rides atop the  asthenosphere  (the two components of the  upper mantle), is divided into a number of  plates  that are continuously being created and consumed at their opposite  plate boundaries. accretion occurs as mantle is added to the growing edges of a plate, associated with  seafloor spreading. this hot added material cools down by  conduction  and  convection  of heat. at the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of  subduction  usually at an  ocean trench.[3]this subducted material sinks through the earth's interior. some subducted material appears to reach the lower mantle,[4]  while in other regions, this material is impeded from sinking further, possibly due to a phase transition from  spinel  to  silicate perovskiteand  magnesiowustite, an  endothermic reaction.[5]the subducted oceanic crust triggers  volcanism, although the basic mechanisms are varied. volcanism may occur due to processes that add buoyancy to partially melted mantle causing an upward flow due to a decrease in density of the partial melt.secondary forms of convection that may result in surface volcanism are postulated to occur as a consequence of intraplate extension[6]  and  mantle plumes.[7]it is because the mantle can convect that the  tectonic plates  are able to move around the earth's surface.[8]mantle convection seems to have been much more active during the  hadean  period, resulting in gravitational sorting of heavier molten  iron, and  nickel  elements and  sulphides  in the core, and lighter  silicate minerals  in the  mantle.