A brief introduction to genetics

Published on March 31, 2019   52 min

Other Talks in the Category: Genetics & Epigenetics

Hello, everybody. My name is Dr. Lawrence Bellamy, and I'm a senior teaching fellow at the University College London in the UK. I'm going to be giving you a brief introduction to genetics.
I would like to begin with a graph. This graph is a reason to be optimistic; it shows how life expectancies in the UK have changed over the past 150 years. Were I giving this lecture 500 years ago in say, the time of William Shakespeare, two out of three individuals will be dead by the age of 21. The reason why life expectancies were so low is that people were dying from what was called "The enemy outside." They were dying from infections such as cholera or tuberculosis; they were dying from things such as famine, the cold, or even war. But, today we've kind of controlled this enemy outside, but there is some bad news you all have to die, eventually. But, today we die from things that referred to as the enemy within. Today, we're dying from diseases such as diabetes, cancers, dementias, all of which, unquestionably, have a genetic component. That's not to say maintaining health isn't important, eating healthily and doing exercise, is important and how your genes interact with the environment that they're in is another lecture itself. But, our genes are certainly determining our health today.
Your human genome is essentially an instruction booklet on how to make you. It is made up of four subunits which we call bases: Thiamine, Adenine, Guanine, and Cytosine. We often refer to them as a single letters T, A, G and C. Your human genome is about 3.2 billion letters long. That genome is packed into every single cell of your body. So, you have an awful lot of DNA. If I were to take all the DNA in your body, if I lined them up end to end, it would stretch from the Earth all the way to Mars, and back again about 150 times. How this DNA gets into each individual cell is, again, an interesting topic in itself. When we first sequenced the human genome, we started looking at it, and we started asking questions. I like to think that being the complex beautiful creature that I am, that I am made up of lots of individual parts. But, when we start looking at the genome, we began to realize, well that's not really true. If you look at the number of gene or DNA sequences, which code for proteins and proteins are essentially the building blocks to organic life, there are only about 20,000 protein-coding genes within our genome. That's not very many. If I looked at the number of components it takes to make the bus that I took to work this morning, if I broke down that bus into the panes of glass, the nuts and bolts, the washes, the rubber tires, that, too, will be about 20,000 components. I like to think that I'm more complex than a London bus, but from some perspective, I'm not. The way complexities built up in creatures, such as us, is that different genes will interact with each other in different ways. That is really a focus of genetic research today.