Answer:
Explanation:
A Stem cell is a cell with the unique ability to develop into specialized cell types in the body. They serve as raw materials to the body. cells from which all other cells with specialized functions are generated.
Cells in the body have specific purposes, most cells are specialized to perform particular functions, such as red blood cells that carry oxygen around our bodies in the blood, but stem cells are cells that do not yet have a specific role and can become almost any cell that is required.
Stem cells provide new cells for the body as it grows, and replace specialized cells that are damaged or lost. They can divide over and over again to produce new cells. As they divide, they can change into the other types of cell that make up the body.
Stem cells are important for living organisms for many reasons. In a blastocyst, the inner cells give rise to the entire body of the organism, including all of the many specialized cell types and organs such as the heart, lungs, skin, sperm, eggs and other tissues.
Given their unique regenerative abilities, stem cells offer new potentials for treating diseases such as diabetes, and heart disease.
Stem cells originate from two main sources
1. Adult body tissues
2. Embryos.
Adult stem cells. These stem cells are found in small numbers in most adult tissues, such as bone marrow or fat. Compared with embryonic stem cells, adult stem cells have a more limited ability to give rise to various cells of the body
Embryonic stem cells. These stem cells come from embryos that are three to five days old. At this stage, an embryo is called a blastocyst and has about 150 cells. they can divide into more stem cells or can become any type of cell in the body. This versatility allows embryonic stem cells to be used to regenerate or repair diseased tissue and organs.
Two mechanisms ensure that a stem cell population is maintained:
1. Asymmetric cell division: a stem cell divides into one mother cell that is identical to the original stem cell, and another daughter cell that is differentiated.
When a stem cell self-renews it divides and does not disrupt the undifferentiated state. This self-renewal demands control of cell cycle as well as upkeep of multi potency or pluripotency, which all depends on the stem cell.
2. Stochastic differentiation: when one stem cell develops into two differentiated daughter cells, another stem cell undergoes mitosis and produces two stem cells identical to the original.
