[MUSIC] Hello, and welcome to Genes and the Human Condition, From Behavior to Biotechnology. My colleague Dr. St. Leger and I are excited to take you on this adventure, examining the balance of genes, expression, and the impact of environment. And how they work together to make you uniquely you.. You don't need a strong background in biology or genetics to do well in this class. You just need to be interested in the material and have a passion for learning. Did you realize that you might have the genes to grow really tall or have an incredibly high IQ? But you were starved in nutrients while you were developing in your mother's womb, or during your formative childhood years, the expression of those genes could be altered. We'll discuss how humans have and continue to use what we know about genetics and biology to manipulate the world around us. This field of genetics is called biotechnology. Genetics is the study of heredity, or how traits are passed on from one generation to the next. We're gonna talk a lot about vertical gene transfer throughout the semester and through the process of sexual reproduction. This occurred when you inherited your genes from your parents, and will occur when you pass your genes down in vertical fashion to the next generation. The molecule of all living organisms, including us, that we use to pass on our genetic information is called DNA, deoxyribonucleic acid. DNA is the universal language of genetics, and we have a lot of it. Almost every cell in our body has over two meters, or six feet worth of DNA. It is very thin, thread-like, and double-stranded. And just like a thread, it's organized by wrapping it around a spool. Your DNA is organized by wrapping it around a very special protein called histone. So how does a molecule pass on genes? You could think about DNA like a cookbook. It has a recipe, and every recipe you need to make you, you. Now, that's one pretty important cookbook. And with anything that's important, you're going to want to protect it and keep those recipes safe. Our DNA is housed and protected in the nucleus of our cells. In fact, that DNA is so important, we don't use it directly and we never allow it to leave the nucleus. Only specific regions of the DNA are transcribed into RNA, ribonucleic acid. RNA is a cheap, single strand molecule that can leave the nucleus. We use the RNA to express our genetic code instead of using our DNA directly. So, would you be willing to take out your family's heirloom cookbook and risk the chance of it getting ruined every time you cooked a meal? Probably not. It makes much more sense to copy each recipe down on a separate piece of paper that you don't mind spilling food on. Transcribed RNA is our genetic piece of paper to ensure that our family's genetic recipe stay protected. That DNA cookbook has about 22,500 recipes, or genes. And we can make at least 10 times more proteins than the number of genes. So what does that mean with the cookbook analogy? Well, that means you have about 22,500 different recipes. But you'd only use them to make 22,500 different meals. You could make ten times more meals. Later on we'll talk about how these recipes can be modified to make even more than those 22,500 meals. We also have two sets of chromosomes, one from your mother and one from your father. Because of this, we're called diploid. And these chromosomes are present in homologous pairs. We have 23 pairs of chromosomes. Each pair is going to be alike in size, structure, and carry similar information for the same kind of traits. We call those chromosomes homologous. What that means is when we look at the cookbook analogy, that you actually have two heirloom cookbooks. One from your mother's side, and one from your father's side. In every genetics class, we have to talk about something called the central dogma of biology. The dogma states that DNA is used as a template to generate RNA. Just like we talked about with that analogy of the cookbook. That process is called transcription. The RNA codes a specific sequence of amino acids that are gonna be linked together to form a protein. That process is called translation. And what we see is that different cell types in your body all have different RNAs transcribed, and in turn, different proteins translated. But how is that possible if almost every cell of your body has the exact same DNA? Well, in different cell types, different DNA sequences can be turned on and off as part of a process called differentiation. Our bodies can control what genes are turned on and how much RNA you transcribe, as part of a process called gene expression. So how does your body know which amino acids to use and the right order to put them in? Well the DNA determines all of that. The string of amino acids is called your primary structure of a protein. That again is determined by your DNA. The secondary structure is how the different amino acids interact with each other. And the tertiary structures, the 3D-shape of a protein. And what we're gonna see is that, that shape or form of a protein directly relates to its function. But also we have proteins that have a really complicated structure, that are composed of multiple sub-units that come together. And those proteins are said to have a quaternary, or four-dimensional structure. So DNA mutations can lead to irregularly shaped proteins because of the relationship I just talked about. DNA codes for the linear sequence of amino acids. So if there's a mutation in the DNA, that can lead to an improper amino acid sequence in the protein. That can ultimately effect the folding of the protein. And remember, changing the shape of a protein can in turn change the function of a protein. A great example of this is the sickle cell trait. It's due to a substitution mutation in the hemoglobin gene, which causes one amino acid to be substituted for another amino acid. And this changes the shape of hemoglobin found in red blood cells. That, in turn, changes the shape of the red blood cells. And that ultimately alters the function of those cells. A red blood cell with an altered shape has an altered phenotype. Your phenotype are your specific physical or observable traits. Your phenotype is determined by your unique interactions of your genes. And that collection of your genes is called your genotype, and how your genes interact with the environment. So that interplay, your genes and the environment, is what makes you, you. And that's one of the many interesting things we're gonna be discussing throughout the semester. [SOUND]
