Hello, my name is Beth Young and I'm a geneticist and that means I  study DNA and today I want to talk  to you about my job and what DNA is. Have you ever wondered why people in a family look alike? Well, that perhaps sometimes tell you you look like your aunt, or maybe even your cousin. Well, that's because people in the family share some of the same DNA. And DNA codes for genes and genes are the instructions that tell your body how to grow and develop. So if we think about the human body. We're made up of several trillion different cells within each of these cells, there's a nucleus, and within the nucleus there are these things called chromosomes, and each chromosome is made up of really tightly packed and wound DNA. So what does DNA look like?  Well you remember I said that in every cell we have chromosomes. In fact we have 22 pairs of chromosomes labeled 1 to 22 with chromosome pair number one being the biggest and  Chromosome pair number 22 being the smallest.  And then we also have the X&Y  chromosomes and these are the chromosomes that tell your body body whether to grow into a girl or a boy. So for girls we have two X chromosomes, but no Y chromosome. And then if we look at the chromosomes from a boy, they still have those same 22 pairs 1 to 22. But they have 1X chromosome and one Y chromosome. And then if we unwind that really tightly packed DNA that makes up chromosomes,  we find what we call the genetic code.  And if you think about our alphabet has 26 letters, the genetic code just has four  letters A T G & C and together.  They spell out all the instructions to make you grow into you. So I've got a few facts. You know things you might not know about DNA. So we call all of that DNA code in a single cell a genome, and we call each of those letters a base pair. And the human genome. So all the DNA  in one cell has 3.2 billion letters.  Spelling out instructions. And if you took all of the DNA in your cells and laid it out in a line, it would reach to the sun and back nearly 70 times. So all of that DNA wound up really tight and packaged up inside of you. And then if you spoke one letter of DNA per second, 24 hours a day, it would still take you 100 years to read out the whole of the genome in one single cell. So that's how much information is contained within your body. And this is something that I think is really interesting if we think about that genetic code, those 3.2 billion letters. We share 99% of it. 99% of our genetic code is the same as the genetic code for a chimpanzee. 98% of our code is the same as that that gorillas have. In 97% of that code is the  same as orang-utans So to me, that that shows that most of our code in ourselves is telling the body how to grow things that we have in common with these animals. Things like hearts and eyes and ears. But what I think is really funny. Is it? Although we've got all this in common with these really high order animals. We still share 60% of our DNA with something as simple as a banana, so quite a lot of the material. More than half of it in our body is coding for very basic types of cells. So I'm sure it won't surprise you to hear that if we share that much of our DNA with a chimpanzee, we each have a lot of our DNA in common. In fact, every human on the planet shares 99.9% of our DNA code. So that means our DNA between you and me is very similar. And it's that remaining point 1% of our DNA that gives instructions for things that make us look different, like our hair colour or eye colour or height or skin colour. So changes in our DNA like spelling mistakes, can sometimes change. The instructions that are telling  your cells how to grow into what they are.  Sometimes these changes are quite small and have no effect on how the cells grow, but also sadly sometimes they can cause disease. And I've got a few things here to think about about genetic diseases. As I said, within families, we share our DNA, so sometimes we have diseases that can be inherited. passed down from one  family member to another, but also sometimes they can be completely random. They can affect any organ within their  body because every organ grows  depending on its DNA instructions. So depending on where that  change is, the spelling mistake,  different organs can be affected. And the effect of the change or the spelling mistake can be really variable.  It might be quite mild and you will never know you've got that change. But also sadly sometimes it can be quite severe and make people quite poorly. And also different disorders are caused  by different spelling mistakes.  It might be a mistake in just one gene,  or it might be a mistake in lots of different genes that added together make the disease. So this is where my job comes in. What I do is look at people's DNA and use it to try and help them diagnose the disease, and we can do this on two levels. Do you remember I said that in every cell we have these pairs of chromosomes, so some of the testing we do is just looking at the cells and counting the number of chromosomes, making sure that's the right number and there's no bits missing or added on. Or sometimes we unwind the DNA and try and look for spelling mistakes. I was just going to give you a couple of examples of some of the testing and do. I'm sure some of you will have heard of a condition called Down syndrome. People with Down syndrome can sometimes have some trouble learning and might be slower to develop skills such as walking and talking. And they can also sometimes have heart problems and Down syndrome is caused by something we called trisomy 21. And all that means that is in the  cells of someone with Down syndrome.   Instead of having two chromosome 21s,  they have three and we can do that just by looking at the cells. And counting the number of chromosomes present.  Or an example of where we're looking  for spelling mistakes is a disorder called cystic fibrosis or CF,  and if we suspect someone's got  cystic fibrosis, we'll look for a spelling mistake in the CFTR gene. So this here is meant to show you how we do that sequencing. So we have some software that we can do our reading on this top line here shows the pattern that we expect to see the pattern of bases in a healthy individual and then this line here shows the pattern of bases in the patient that we're interested in and what the software can do is look for any differences and that's  what it's showing us in the bottom here.  And the software can see. that there's a change here.  This extra red peak in our patient. That one spelling mistake has caused CF in this person. And people with CF get mucus in their lungs and they can sometimes find it quite hard to breathe. Now we talked about how much DNA we have in common. One of the things that's interesting is that identical twins are the only people in the world who share 100% of their DNA with each other. Do you have any twins in your class or do you know anyone who's twins? So although they share all of their DNA with each other? They don't necessarily look the same or act the same, and that's because there's so much more to us than what our genetic code is. Our genetic code tells the machine that's our body how to grow and develop, but we as humans are so much more than just that code or machine. Some of the things that can impact on how we look, our environmental factors, and this is the word we use to describe the conditions we grow up in and live in. We all know that healthy eating and exercise can help us to grow strong, but did you know things like the quality of the air you breathe, whether this pollution or how much sleep you get can also have an effect on how tall you grow. And then there's our behavior that undefinable thing that makes you you that no genetic code could explain. For example, my DNA tells me my hair should be brown,  but I can colour any colour I want,  and at one point I had bright red hair because I felt like it that's not in my DNA. That's just what I wanted to do and we all dress differently and look differently and express ourselves in different ways. And we all have different interests and skills. So although we have this  genetic code that tells our body how to grow and develop. There's so much more that makes you the individual that you are. So what I want you to do now is to think about your own identity. What makes you you and how would you describe yourself to somebody else. We would like you to take your piece of card and have it go at decorating it with all the things that make you feel you are like you are and to get you started. Here's an example of what I've done for myself so it could be a physical characteristics like  your eye colour or hair colour.  Here's me being a scientist with my brown hair and brown eyes below here me and my husband and our children Ali and Zach and they share some of their DNA with me. But it could also be things like what you love and your hobbies and interests. I've got a cat Snowbell and I love her very much. I also love to swim and I love to read and those aren't things that come out of my DNA. That's just part of who I am. And if you're doing this, have a think about where each part of your identity might have come from. Is it something you might have inherited from your parents, or is it something that's just unique to you?  We will be really interested to  see what you produce.