Transcription
Captions are enabled! To turn them off, click the CC button in the bottom right! Follow us on Twitter (@AmoebaSisters), and on Facebook. I want you to think for a moment about your favorite food. What is it? Pizza? Macaroni and cheese? Chicken salad? Sushi? Well, we all have different food preferences, but food is a source of large molecules needed for life called biomolecules. There are 4 major biomolecules, which make up all life, and this will be the focus of this video. Before we get into the details about the 4 biomolecules, we need to talk about a very important vocabulary word: monomer. A monomer is a building block. If I have a large substance, the parts that make up that substance are called monomers. Just like building blocks. We will be talking a lot about biomolecules today, because we need to understand what molecules are made of. And we need to understand molecules because they are the basis of the components of life. So let's introduce the 4 biomolecules now and talk a little about their functions. We'll start with carbohydrates. Carbohydrates. Well, carbohydrates are something you've probably heard about when people talk about diets. You know, they try to cut back on carbs, or maybe they want a lot of carbs... Diets always come and go. Pasta and bread are examples of carbohydrate-rich foods. Carbohydrates are actually a very important source of energy. In fact, this is one of the biggest functions of carbohydrates. They are a quick and fast source of energy. If you're a marathon runner, you might want to eat a lot of carbohydrates the night before the race. A lot of marathon runners do this. It's called carb loading. It's a big pasta dinner the night before the marathon. Now, carbohydrates have a monomer again. Remember, monomers are the building blocks. The monomer for carbohydrates is called a monosaccharide. And I know that's a big word, but monosaccharides make up carbohydrates. The next one is a group known as lipids. There are 2 different types of building blocks. One type of building block is called a fatty acid, and the other type is called glycerol. Now, examples of lipids include butter, oil, and cholesterol. Lipids have a lot of great functions. You might think lipids are bad... How good can lipids be? Well, that just depends on when you put it in context. For example, do you know those really cute seals you see on calendars? They have that fluffy white fur. They're actually called harp seals. Well, they actually look just like that when they're babies. When they grow up, they're not quite as cute. But at a very young baby stage, they actually have a lot of this fur that they were born with that helps to keep them warm. But over time, they have to develop blubber. It's fat, and it helps to keep them warm. Lipids are great for insulation. Also, you might not think lipids are related to energy, but lipids are a great source of long-term energy. They can store energy for a long time, a very long time. Say, for example, you wanted to swim across the English Channel. That's like 21 miles of swimming. The fastest swimmers might be able to do it in 7 or 8 hours, but it might take a lot longer than that for the average swimmer. Like 25 hours, and that's a lot of swimming. Well, you'd want to make sure your body has enough fat – enough stored fat – that it can draw on. Because after you burn those carbohydrates (remember carbohydrates are the quick source of energy), you might not have enough stored energy unless you have some fat on hand. Lipids also make up cell membranes, so they are very important for life because all living things are made of cells. Of course, an excessive amount of lipids can be a bad thing for your health. Remember, it's all about moderation. Okay, next, proteins! When you hear about proteins, you might always think about restaurant salads. They say they have a lot of protein in them, and that they help build muscle. Protein is a great thing for building muscle. Foods that are high in protein include meat and many types of beans. The monomers of proteins are amino acids. So sometimes you'll see these labels that say, "This contains 20 amino acids in this food." Really, they're just trying to say it contains protein, and proteins are made of amino acids, so that's just some fancy advertising for you. But in addition to being important for muscle development, protein is also very important in other functions like immune system functions and acting as enzymes. Remember, enzymes are made of proteins, so proteins are important for the body. Now, when we start talking about genes – DNA genes, not the jeans you wear – DNA codes for proteins that are very important for the structure and function of the body. Another large biomolecule is known as nucleic acid. Nucleic acids include DNA and RNA, which we'll get to when we get to genetics. They have a monomer called a nucleotide. This will be easy for you to remember because the pronunciation of nucleotide sounds close to nucleic acid. If we consider DNA and RNA, they are both involved in genetic information for coding your traits. They are found in a lot of your food, because whenever you eat something that comes from something living, it still contains DNA. For example, when you eat a strawberry, you're actually consuming all the cells that make up that strawberry. In the nucleus of every strawberry cell is DNA. Plants and animals both contain DNA. In fact, any type of life must contain nucleic acids like DNA to direct active cells. So we've just powered through introducing the 4 biomolecules by providing examples, exploring their monomers, and giving some general functions. One last very important part we should mention is the structure of these biomolecules. Understanding the structure can help in predicting their properties and easily being able to identify them. One thing I would say for students to do is write the 4 biomolecules in this same order that we've explained them: carbohydrates, lipids, proteins, and nucleic acids. Then remember this mnemonic that goes with these 4 biomolecules. Chon, chon, chon, chonp. Instead of chomp at the end with an "m," it's chomp with an "n." C represents carbon, H for hydrogen, O for oxygen. So carbohydrates, lipids, proteins, and nucleic acids all have that CH in there. It's just that proteins and nucleic acids also have N, which is nitrogen, and nucleic acids additionally have P, which is phosphorus. So again, Chon, chon, chon, chonp – the main elements in the 4 biomolecules. Now, these elements are arranged differently in the 4 biomolecules – like a ring arrangement or a chain arrangement. It's important to explore the arrangement of elements in biomolecules, because the structure of that arrangement greatly affects the function of the biomolecule. So head to Google to discover some illustrations of biomolecule arrangement. Well, that's all for Amoeba Sisters, and we remind you to stay weird.