Describe the role of stem cells in multicellular organisms?
Good question! To start, a stem cell is a cell with the ability to self-renew indefinitely. This means they can divide themselves unlimited amounts of times. This is unlike other normal cells which have a limited number of cell divisions. Stem cells are important to maintain ALL of our cell populations. For example, at the bottom of our skin's outer layer, the epidermis, are a one cell thick layer of skin stem cells. These divide, remain in their positions on the bottom whilst their daughter cells move forward towards the skin surface. Eventually they die when they reach the surface of our skin. They are also important for making the cells of our blood and immune system, as well as helping repair, regeneration and healing of tissue after injury. They form our nerves, bones, fat stores as well as sex cells, the sperm and ovum. The rest of my answer is a little advance, so maybe only read if you are an A-Level or University student! Many people think that pluripotent cells, are always stem cells. But this isn't true! For example there are early embryo cells at the "morula stage" that can give rise to all adult (somatic) cells, meaning they are pluripotent, but they are not stem cells as they do not have the ability to self renew. It is important to mention also the difference between cancer cells and stem cells, as an important hallmark of cancer is gaining the ability of unlimited self renewal. the main difference is that stem cells also ALWAYS retain their normal phenotype, meaning they cellular biology does not change. Cancer cells show different phenotypes, meaning they look different under a microscope. They are different to the normal tissue at a cellular level. If you would like to learn about this in a more simple way, or hear about the fine complex details, message me! Happy to help. Thanks, Ben.
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