Intro Quiz: Case study of Betty Hay

Video: Case study of Betty Hay

﻿Welcome to lesson 16, in the cells, tissues and organs topic. This lesson, we're going to look at a case study of someone called Betty Hay. This is a scientist who contributed loads to the worlds of biology. So we're going to look at this in detail. For this session, you're just going to need a pen and a piece of paper. Make sure all distractions are away from you and you're ready to go. In this lesson, I'm firstly going to introduce who Betty Hay was. We're then going to have a look at her contribution to cell differentiation and regeneration. We're then going to have a look at how this relates to stem cells and also how she contributed to extracellular matrix. Betty Hay was a scientist, born in 1927 and died in 2007. Her education started at Smith's college in 1944. This is where her love of biology started to grow. She worked closely with her professor, Meryl Rose. They studied looking at limb regeneration from amputated limbs in salamanders. They used transmission electron microscopy, which is a gun that shoots electrons at high speed. And they looked at how these limbs could regrow. From here, she went onto John Hopkins Medical School rather than going to graduate school. She continued to work with Meryl Rose through summer camps, and finally ended up being an assistant professor at John Hopkins. She then went on to mentor many people in the science industry. She became an advocate for women in science. Quick fire question, what animal was amputated in Hay's research? Say your answer out loud. Good! It was salamanders, option three. Which medical school did Hay end up studying at after working for Meryl Rose? Good! We should have got John Hopkins. Many animals can regenerate, and we know a wealth of knowledge about this now. Starfish, if they lose an arm can regrow one. Sharks can have up to 24,000 teeth in their lifetime. That's because when they lose one, they can grow another. Flatworms, if they are cut in half, can form two whole new worms, which is pretty amazing. Lizards, of some kinds, if they have their toe removed, can grow another one and it can be fairly grown within about nine months. In humans, the liver can regenerate. If parts of the tissue become damaged, the remaining healthy tissue can replace it. The healthy cells will keep copying themselves until the liver gets back to its normal size. Quick question: Which organ in the human body can regenerate? Say your option out loud. Good. We should have got the liver. Name an animal that can regenerate. Good.So we could have had shark, lizard, starfish or flatworm from the video. You might know some of your own. We're now going to go on to have a look at stem cells. Hay's findings was significant. She found that when the salamanders had an amputated limb, specialised cells in the body, such as the nerve cell could de-differentiate and become stem cells. Stem cells just means it's not specialised, it can become any specialised cell in the body it needs to, and then it would re-specialize to whatever was required to regenerate a perfectly new working limb. Stem cells are really important. This topic comes up later at GCSE. Stem cells are cells that have not yet been differentiated, so they are not specialised. You may have already looked at specialised cells before. If not, you can see there's a range of them on the screen, in the images. Specialised cells are cells that have a particular function and have adaptations that make them exceptionally good at their job. So for example, a nerve cell carries electrical impulses around the body. So, it has a long axon where the messages will be sent and have a fatty sheath around the outside. This will insulate it to allow the message to travel faster. Muscle cells, can contract and relax, just like our biceps and triceps. They also contain lots of organelles called mitochondria. This is where respiration will take place, so there's the release of energy. There are three places that we can get stem cells. The first one is embryos. Embryos are formed from fertilised eggs. So once that sperms enter the egg and it's become fertilised, it will then form an embryo. An embryo is just a divided cell; it's a ball of cells. All of those cells will not be differentiated at this point, but they can become differentiated into any cell they need to. That will then obviously form a baby. Adult cells are slightly different. Adults are limited in where they can get stem cells. For example, they can get them from the bone marrow. So that's the middle part of our bone. That's quite an extensive operation in order to remove those. Plants can also produce stem cells. And you find these in the meristem. The meristem can also produce any specialised cell. Stem cells are really important. For example in plants, we could use these stem cells to clone important plants, such as grains or other crops, such as rice, in order to make sure that we're producing enough for the population. It could also be to help any rare plants stop going extinct. Many parts are used for things like medicines. That's really important. For humans, we might need them to treat a medical condition. There are many different types, such as cancer or paralysis or even diabetes. There are two ways that we can then help to treat these. We can use embryonic stem cells, which are really beneficial. They can become any specialised cells that we need. For example, blood cells, muscle cells. However, there are ethical issues. Because we are removing it from an embryo, it could cause an embryo damage. We could get them from adults. Adults can give consent to taking them. It is an extensive operation to remove them from the bone marrow or other places. However, they are limited to what they can turn into. They cannot turn into the full range of specialised cells. So for example, if we remove them from the bone marrow, they can only become immune cells. So they can only become related to the blood. Quick fire questions! What is an undifferentiated cell? So, say your answer out loud. Good. It is a cell without a particular role that is not specialised. What is an embryonic stem cell? Pick your option. Good. We should have picked option one. It is a cell found in embryo that can differentiate into any type of cell. Can you state a disadvantage of using embryonic stem cells for treatment? Say your answer out loud. So we should have got ethical issues. Can you state a disadvantage of using adult stem cells for treatment? We should have got, it is a limited or narrow range of cell types it can turn into. We're now going to have a look at the extracellular matrix. So, Hay's turned her attention away from salamanders and starts to look at bird eyes. She wanted to look at the outer layer of the eye called the cornea. It is the protective layer over the front of the eye. She looked into these particular cells called cornea epithelium cells. She found that these produce a substance called collagen. Collagen, was a type of extracellular matrix. Now, this is really important. When we look at cells in science, we tend to look at what's inside the cell. The extracellular matrix is what is on the outside. So it's the bits that make up the space in between those cells. So for example, if we had a jar full of pebbles and sand, the pebbles would be the cells. The extracellular matrix is all those grains of sand that make up the in between parts. And this is actually found to be really important, when we look at how tissues form to make organs. The extracellular matrix has a few different functions that are really important for plants, animals and even unicellular organisms. So, the extracellular matrix, is actually a bit like a highway. When we have something like a cut, and we need to heal and we start to get the scabbing form on our skin, that's because substances travel along the extracellular matrix in order to go and locate the cut. Hay started to isolate, to grow, and even take pictures of the cornea of the bird eye. She found that the matrix could even tell other cells what to become. Now, when they presented this idea to other scientists, they even dismissed this idea at first, but now it's well known. It's really important. And she contributed these key ideas. The other scientists have gone on to then recognise, but only to advance that also. So our knowledge and now of extracellular matrix is now extensive. Extracellular matrix, as you can tell, is very very important. So we're very thankful for Hay's contribution. The extracellular matrix, is that part around the outside of the cell, like we said, has got many different, important jobs. It has number one, collagen. So that stuff that called the cornea produces collagen, it's really important for strength. It can also help us to produce blood clots. Now, blood clots are obviously important. We don't want to bleed out and die, so that's always good. And it can also help us to regrow healthy tissue. And heal our body. So obviously this is a very, very important part. Quick fire question! What was the key finding from Hay's looking at the bird's eye? Say your answer out loud. So, the answer was, the key finding was epithelial cells could produce collagen. That collagen, as you should know, is a protein that makes extracellular matrix. Give one reason why extracellular matrix is important. So we should have said, it can help with blood clotting, regrowth and repair and strengthening of cells. Well done if you remember those! Hay's not only contributed so much the world of biology, but she also was an professional leader in Africa for women in the science industry. She was one of four women to graduate from her class and went on to mentor so many women in the industry and put them in contact with other people to enable them to progress. She was president for multiple professional societies, which was unheard of at the time. And she was the first female to become chair of department of cell biology, at Harvard university, which is amazing. She was a powerful woman who has helped this industry be less male dominated, which is fantastic. It's now over to you. Pause the video and complete the following task. Can you explain the importance of Betty Hay's findings? I want you to include the idea of cell regeneration, to make sure you can define that, give examples. Can you also link that to stem cells? So what are stem cells? Can you give me an example of what they might turn into? Where we might find them? And also give a small description of extracellular matrix and it's importance. I've given you key words to help you. Pause the video now and then resume when you're ready. Okay, let's go through and mark your answers. So Hay discovered salamanders could regenerate an amputated limb, meaning that they could grow cells to replace those missing ones. So examples of that, could be, animals such as starfish or lizards or sharks with their teeth. The regeneration of cells means the differentiated cells become undifferentiated stem cells again. Now don't forget, stem cells are just undifferentiated cells; they are not specialised. Stem cells can be found in embryos, adults and plants, and are cells have not become specialised. Examples of specialised cells include: nerve cells, ciliated cells and sperm cells. The body can then instruct the cells on what type of cell to become. This is similar to the liver. When it is injured, those cells can regenerate to replace the damaged ones, until the liver is back to its original form or size. Hay's also found the cornea on bird cells to contain extracellular matrix. The extracellular matrix, can tell other cells what to become. Collagen is an example of extracellular matrix, which is important for providing structure. You could also say that the extracellular matrix was useful for blood clotting and healing and regrowth of tissue. Well done if you got all of those! I don't know anything that you might've missed. It's now time for you to go and complete the exit quiz. Well done. Goodbye.

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This lesson is dedicated to Betty Hay and looking at her contribution to the world of cell biology.

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