[MUSIC] Hello, everyone, welcome to my Coursera class, Biochemical Principles of Energy Metabolism. My name is Seyun Kim, I'm an assistant professor of Department of Biological Sciences at Korea Advanced Institute of Science and Technology, KAIST, in Korea. So the ultimate goal of this class is about bioenergetics. So I'm going to give you a conceptual understandings of how our cells and body can, Metabolize many different types of nutrients to meet the energy demands you require to sustain life. And finally, I'm going to give you biochemical principles underlying the metabolic syndromes or metabolic dysfunctions. For example, obesity and type 2 diabetes. This course is composed of total seven weeks, it's total seven weeks. So in the very beginning, I'm going to give you the introductory information about concept of metabolism and what energy is. And then what about the most fundamental unit of energy for life, I mean ATP. And then I'm going to further introduce the functions of metabolic organs and what enzymes are. And I'm going to begin with the glucose digestion. And during the class, I'm going to emphasize the importance of glucose metabolism. In particular, cellular respiration to extract energy, molecules. And I'm going to also introduce the photosynthesis. Which is the vital biochemical process for sustaining energy metabolism in this planet, I mean Earth. And them I'm going to further explain the biochemical processes of fat metabolism. And further, I'm going to, Introduce and explain the importance of pancreas. And more importantly, the insulin hormone actions. And I'm going to summarize the importance of diabetes mellitus, which is one of the key medical complication developed from the insulin dysfunction. And finally, I'm going to give you different types of modes of bioenergetic regulations in life. At the very beginning, starvation-related biochemical processes. And what types of metabolic responses occur by the exercise in our core metabolism. And further, cancer cell-specific metabolic processes. And finally, I'm going to wrap up this class by emphasizing the importance of gut microbiota in the regulation of energy metabolism. So let me begin with the definition of metabolism. So metabolism comes from the Greek word, I believe, metabole, I believe. And originally, that means change, and change of what? So definition of metabolism is life-supporting biochemical reactions required for transformation. That means change, change of what? Change of chemicals, In living cells, in living organisms. So there are many topics available in the field of metabolism biology. So apparently, the energy is the key main topic and the key issue of this Coursera class. And other areas of metabolism biology involve cellular building blocks. Like how proteins, and lipids, and nucleotides can be synthesized and transformed. And another area of metabolism biology is drug metabolism. How xenobiotic drugs, chemicals, can be transformed. And can be excreted throughout our body systems. So obviously, this course is about energy, it's about bioenergetics. This review cartoon showing that high energy-containing chemicals like, simply, speaking food, carbohydrates, fats, and other nutrients. How those organic compounds can be transformed throughout our body into our body's energy currency. We are going to study further ATP. And how chemical waste throughout those metabolic processes, like CO2 and water, can be generated and can be released. Before we get into biochemical details one by one, first we have to think about our ecosystem. So ultimate source of energy comes from the sun. So this solar energy can be transformed Into usable energy by autotroph. Auto- means self, autotroph means self-feeding organisms. In ecology, we just simply call it producer. Producer, like plants and photosynthetic bacteria. Those organisms are very special in terms of producing organic compounds. Organic compounds like high energy-containing organic compounds like carbohydrates, like glucose. And byproduct, they release oxygen. And what about human beings and other organisms called heterotroph, so called consumer? And humans are like a fungi. And many animals and heterotrophic organisms cannot produce organic compounds by their own. We are 100% relying on the product made from autotroph. And ultimate source of energy is sun, that's the point. All right, so by definition, metabolism is the transformation of chemicals, chemicals of living cells and living organisms. So what types of chemicals do we have? So you're looking at the plants, and fungi, and mouse, and humans, and worms, and cells. And what types of chemicals are involved in the activities in life? So obviously, as you know, the water takes 70% of these cells. So remaining chemicals, Remaining 30% of chemicals further categorized into different classes. So polysaccharide, polysaccharide means the carbohydrate's polymer takes like 2%. And proteins, so that's major constituent of chemicals, so the chemicals, like 15%. And DNA and RNA, those nucleic acids involved in the flow of genetic materials and the storage of genetic information takes 7%, which means a lot. And those molecules are collectively called macromolecules. So macro- means large, so in terms of size, those molecules are big, simply speaking. And only a few percent of cellular chemicals, the so-called small molecules. So the cut-off is 1,000 Da, so below 1,000 Da, we call. Those chemicals are small molecules. And further, we can take like minerals, sorry about that. Minerals like calcium or iron, + many metabolite. Metabolites, which are produced by chemical reactions. So there are four types of major macromolecules. First one is proteins, and building block is amino acid. And second class is lipids. In this diagram, I'm showing the fatty acid of xyloside attractions to form a layer of phospholipids, which is the key constituents of your cellular membrane. And the third one is carbohydrates. It can be further linked to other, Backbones and further polymerized into polysaccharides. The last one is nucleic acid. Those nitrogen-containing bases, that means the genetic material, the core element of genetic material of your genome and RNA can make your nucleic acid. Those four major macromolecules are your main chemicals in your cells. So in terms of metabolic reactions, we have to, Categorize the concept of metabolism by catabolism and anabolism. So by definition, catabolism means all of the metabolic processes that break down biomolecules. On the other hand, anabolism means the biochemical reactions that synthesize biomolecules. Synthesize macro molecules, like proteins, nucleic acid, and polysaccharides. So conceptually, we can summarize the first session of first week by showing this diagram. So high energy-containing food molecules can be degraded into, Like waste molecules, like CO2. And then as well, these processes, we can obtain energy. And this energy can be used to drive the synthesis of macromolecules like proteins, membranes, and your genome, nucleic acid, from simple building blocks.
