in this video we're looking at stem cells so we're going to explain what they are and why they're so important and then take a closer look at some examples namely embryonic stem cells and adult stem cells which are found in animals and then plant stem cells which are found in merry stem tissue in plants let's start with what stem cells are and there are really two key features that you need to know the first is that stem cells are able to divide by mitosis to form more cells so one can divide into two then they can divide into four and so on the second is that stem cells are able to differentiate into specialized cells so one stem cell could differentiate into a specialized nerve cell for example whilst another could differentiate into a skin cell to understand why this is important let's consider how human life starts when a sperm cell fertilizes an egg cell it forms a single cell called a zygote this cell is now its own organism and during the following few days it will divide by mitosis over and over again to form a small group of cells called an embryo we call these cells embryonic stem cells and importantly these ones can differentiate into absolutely any type of cell for example a nerve cell skin cell or blood cell over time these cells continue to divide and also differentiate into all of the other important cells that we need and after nine months or so we end up with a baby now if we fast forward a bit to an adult there are no longer stem cells that can differentiate into absolutely anything like the embryonic stem cells can instead we have other types of stem cells that have already specialized a bit meaning that they can now only differentiate into a narrow range of cells for example in the middle of some large bones there's 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 now the last thing we need to cover are plant stem cells 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 mineral lines importantly plant stem cells persist for the plant's entire life unlike embryonic stem cells which disappear by the time we're fully developed hey everyone amadeus here i just wanted to let you know that we also have a learning platform where you can watch all of our videos practice what you've learned with questions and keep track of all of your progress for both the sciences and maths it's completely free so if you haven't already you can check it out by clicking on our logo here on the right or if you'd like to do the lesson for this particular video we put the link to that in the description down below we've also arranged all the videos for this subject in a playlist for you here that's all though so hope you enjoy and i'll see you next time thanks