Lesson Video: Genetics and Health | Nagwa Lesson Video: Genetics and Health | Nagwa

Lesson Video: Genetics and Health Science

In this video, we will learn how to describe examples of genetic technologies that have improved human health, including the production of golden rice and the Human Genome Project.

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Video Transcript

In this video, we’ll learn more about how genetic technology has improved our health. We’ll discuss what a gene and genome are and some of the things we’ve learned from the human genome project and how we can use this information to improve our health. Then we’ll learn more about vitamin A deficiency and how a special type of genetically modified rice called golden rice can be used to get more vitamin A in the diet.

You may be sitting in a classroom right now surrounded by other students. How related are you to one another? Unless one of your family members is in the class, you might say that you’re not very related. And in some ways, you’re not wrong. You’re certainly more related to your sibling than to a stranger. However, as humans, we’re all related to some degree. It might surprise you to learn that we all share about 99.9 percent of our DNA with one another. And with family members, we’re even more closely related. So what does this mean exactly? And what does DNA have to do with it?

Let’s review what DNA is for a moment. If you take a microscope and zoom in on your skin, you’ll see that it’s made up of cells. If we zoom in on one of these cells, we can see that it contains a nucleus, which acts as a kind of command center for the cell that gives it instructions to grow. Inside the nucleus is a special molecule called deoxyribonucleic acid. This is a bit of a mouthful, so we call it DNA for short.

There’s a lot of DNA inside human cells. And if we were to take it all out and line it up, it would be about two meters in length, which is probably even taller than you are. The reason we can fit all of this DNA into such a tiny nucleus is because the DNA is packed into structures called chromosomes. You can see that DNA molecule here after it’s unpacked from the chromosome. These colored boxes are called base pairs and is the alphabet for the DNA code. This is how DNA can give different instructions.

These base pairs are special chemicals that we call guanine or G for short, cytosine, adenine, and thymine. There’s just four letters in the alphabet for DNA, but the possibilities are endless. By putting these base pairs together in different ways, we can create different characteristics. So if you have blue eyes, this kind of characteristic in DNA can be represented by a certain sequence of base pairs, maybe something like this.

We call the sequence of DNA base pairs that gives certain characteristics genes. So in this example, this blue eye gene gives the instructions for making the blue eye characteristic. This gene is a sequence of base pairs on DNA. So the DNA sequence for this gene might be located in the DNA as shown here. Some people have different-colored eyes, so their eye color gene might be different or something like this. These two sequences are very similar to each other, but there are some differences. There, now any differences are circled in black. These differences are minor but can be enough to have the blue eye or green eye characteristic.

Eye color is one example, but there are many differences in the DNA of one person compared to another. But we’re still about 99.9 percent the same as far as our DNA sequence goes. We know that we’re 99.9 percent the same because we sequenced all the DNA in our cells. And we have a lot of DNA in our cells. Remember if we took it all out, unpacked it, and lined it up, it would be about two meters long. We call this complete set of DNA the genome.

To sequence the genome, we needed to start from the beginning and determine the sequence of all the base pairs all the way to the end of our genome. This was a huge project that we call the Human Genome Project. The Human Genome Project was a massive worldwide collaboration between many scientists. It started in 1990 and was mostly completed in 2003. In all, it cost about 2.7 billion dollars.

After sequencing the human genome, we discovered a lot of interesting things about it. The size of our genome is about three billion base pairs long. That’s a lot of base pairs! Imagine you wanted to read the sequence of the human genome. If it takes one second to read one base pair, then it would take three billion seconds to read three billion base pairs. How long do you think three billion seconds is, one year, five years? It’s actually almost 100 years. That’s a huge amount of time!

We also found out that there’s about 20,000 genes in the human genome. One of the shortest genes is about 800 base pairs long and is called the SRY gene. This gene is needed for the development of the testes. And without it, there would be no biological males. One of the longest genes is the DMD gene. This makes an important protein in muscle tissue. It’s made up of 2.4 million base pairs and is about 0.08 percent of our entire genome.

The Human Genome Project has also led us do genome comparisons with other organisms. This tells us more about our evolutionary history. By doing this, we’ve determined that our genome is 99 percent similar to the chimpanzee genome and is one of our closest living relatives. You might be surprised to hear that we also share a lot in common with mice. Our genome is 85 percent similar to the mouse genome. And as we’ve mentioned, humans are about 99.9 percent similar to one another. This 0.1 percent difference represents about three million base pairs. So the difference between you and me in terms of our DNA sequence is about three million base pairs.

These differences can help us in medical research. By comparing the genome of someone who is healthy to someone who has a disease, we can look for differences. These differences can help us learn more about a disease so we can find cures. The Human Genome Project has given us a way to learn more about ourselves and to fight disease.

By learning more about specific genes in humans and other organisms, we can use them to our advantage. A good example of this is with golden rice and how it can be used to treat vitamin A deficiency. People can develop health problems if they don’t receive enough nutrients in their diet. A nutrient is something that we need to survive and grow. These include carbohydrates, fats, proteins, minerals, and vitamins. Vitamin A is important for the growth and development of our bodies, especially in supporting the immune system and for vision.

Vitamin A deficiency is when you don’t receive enough vitamin A in your diet. This can cause blindness and a weakened immune system, which can lead to death. This is most common in developing parts of the world such as Africa and Southeast Asia. By getting more vitamin A in their diet, this can save up to 2.7 million children from dying every year. In order to get enough vitamin A to overcome this vitamin A deficiency, we actually need more of something else called provitamin A.

Provitamin A is what we get in our diet from the foods we eat. And once it’s inside of our body, provitamin A is turned into vitamin A. So diets that get low amounts of provitamin A will produce low amounts of vitamin A. And this will lead to vitamin A deficiency. But for diets that get lots of provitamin A, this will produce lots of vitamin A. And they will not be vitamin A deficient.

So what food is one that is eaten more than any other food in the world? Rice, although we may not recognize it as a plant, it’s the grains that we cook and eat. Rice is a common food eaten all around the world, and many countries rely on rice as a primary food source. Unfortunately, it contains no provitamin A. So people who rely on rice as a primary food source often don’t get enough provitamin A in their diet and become vitamin A deficient. We can use a technique called genetic modification to change or modify this rice plant so it makes provitamin A.

Genetic modification is a technique used to change the traits of an organism, like this rice plant, by inserting a gene with that trait into the organism. There are several steps involved in genetic modification. First, the gene for provitamin A needs to be extracted from another organism that has the gene. This gene carries the instructions for how to make provitamin A. Next, we have to modify the normal rice plant, which doesn’t make provitamin A, by inserting the provitamin A gene. Now the genome of this plant has the provitamin A gene and therefore has the instructions it needs to make provitamin A. We call this modified rice plant that includes the provitamin A gene golden rice.

When the rice plant has the provitamin A gene, it makes a lot of provitamin A. It makes so much provitamin A, that it actually changes the color of the rice grains from white to a golden color. This is why we call this kind of rice golden rice. Now when people eat this rice as a part of their diet, they’ll get a lot of provitamin A and will no longer be vitamin A deficient. So what does it taste like? Apparently, it grows normally and tastes just like normal rice, except it’s golden in color and a lot more nutritious.

Besides golden rice, other plants have been genetically modified too. Corn is a pretty tasty vegetable for us as well as for insects like this caterpillar. Insects like to eat different parts of the corn plant, and this could have an impact on the plant’s health. Special chemicals called pesticides can be used to kill these insects and protect the plant. However, these have a negative effect on the environment and on our health, so trying to limit their use is important.

So instead, corn can be genetically modified to carry a gene that makes it resistant to insects. This is because the corn plant now carries an insect toxin that only affects insects and not people or other animals. So when the insect goes to eat the plant, it ingests this toxin and it dies. This way genetic modification of the corn plant can reduce pesticide use, and this can be helpful for the environment and for our health.

Another example is with tomatoes. Tomatoes have soft skin and can easily bruise when they’re transported. So we can genetically modify the tomato plant so its skin is more tough and more resistant to bruising.

Genetic modification has many benefits, but some people are worried about eating genetically modified food. This is because we’re eating things that aren’t normally in plants, and this might cause an allergic reaction. There’s been a lot of research on this, and the World Health Organization considers these foods safe to eat.

Now let’s try out a practice question and apply what we’ve learned in this video.

The Human Genome Project found that the genomes of humans are very similar. Roughly, what percent of the human genome is shared between humans? (A) 80 percent, (B) 88 percent, (C) greater than 99 percent, (D) 75 percent, or (E) 50 percent.

This question is asking us about how similar our genomes are. So what is a genome exactly? Our body is made up of cells. Most of these cells contain a nucleus that contains DNA. DNA is a special molecule that gives the cells the instructions it needs to grow. It also gives us different traits and is why some of us are taller and is why some of us have blue eyes, while others have green eyes. These traits are given by sections of DNA that we call genes.

If we unravel this DNA a little bit and look at it more closely, we can see that there’s different sections of DNA that we call genes that code for different traits. So this gene here might code for the trait that makes this person tall, and this one here might code for the eye color trait. If we unravel this DNA even further, you’ll notice the double-helix-shaped structure and these different colored boxes. These are called base pairs and are special chemicals that are like a kind of alphabet. There’s guanine or G for short, cytosine, adenine, and thymine. These base pairs give the instructions needed for our different traits.

Here’s a short sequence of DNA, which is made up of one, two, three, four, five, six base pairs. Different genes have different lengths with unique sequences of these base pairs to code for specific traits. The Human Genome Project was a worldwide project that aimed to determine the sequence of all the base pairs in human DNA. A genome is the complete set of DNA of an organism. In humans, the sequence of our genome is about three billion base pairs long.

Once we had the complete sequence of our DNA, we could then start comparing this sequence between humans. We found that our genomes were about 99.9 percent the same. So even a stranger, who you are not related to, shares more than 99 percent of their DNA with you. Therefore, more than 99 percent of our genome is shared between humans.

Now let’s go over some of the key points that we covered in this video. A gene is a section of DNA that contains the information needed to produce a characteristic or a trait. The complete set of DNA inside an organism is called the genome. The Human Genome Project was a worldwide project that aimed to sequence the entire human genome. We found that the human genome is about three billion base pairs long, contains about 20,000 genes, and that we all share more than 99 percent of our DNA with each other. Finally, golden rice is a genetically modified version of rice that can be used to help with vitamin A deficiency.

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