Stem Cells

• Stem cells are able to divide by mitosis to form more cells, such as dividing into two and then dividing into four.
• Stem cells are also able to differentiate into specialized cells, for example, one stem cell could differentiate into a specialized nerve cell while another could differentiate into a skin cell.
• When a sperm cell fertilizes an egg cell, it forms a single cell called a zygote, which is now its own organism and will divide by mitosis over the following few days to form a small group of cells called an embryo, these cells are referred to as embryonic stem cells and can differentiate into any type of cell, such as a nerve cell, skin cell, or blood cell.
• Embryonic stem cells continue to divide and differentiate into all of the other important cells that we need over time.
• After nine months or so, these cells have developed into a baby.
• In the middle of some large bones, there is a jelly-like substance called bone marrow which contains adult stem cells.
• These cells can divide by mitosis as much as they like but they can only differentiate into different types of blood cells like red blood cells, white blood cells, or platelets.
• The idea with stem cells like this is that they can replace damaged cells to keep us alive but they don't form any new tissues like the embryonic stem cells did.
• Plant stem cells are found in plant tissues called merry stems which are found in areas of the plant that are continually growing like the very tips of the roots and shoots.
• As the plant grows, these unspecialized stem cells will differentiate into all of the cells and tissues that the plant needs like the palisade cells that do photosynthesis, phloem and xylem cells that transport sugars and water, or root hair cells that absorb water and minerals.
• Plant stem cells persist for the plant's entire life unlike embryonic stem cells which disappear by the time we're fully developed.
• In an adult, there are no longer stem cells that can differentiate into absolutely anything like the embryonic stem cells can, instead, there are other types of stem cells that have already specialized a bit, meaning they can now only differentiate into a narrow range of cells.