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Biology: Chemistry in Biology: 14: Carbohydrates
MEDICAL ANIMATION TRANSCRIPT: In this video, we'll discuss carbohydrates. A carbohydrate is an organic macromolecule, which means it's a large molecule containing the element carbon. The hydrate part of carbohydrates means it also contains the components of water, hydrogen and oxygen. Carbohydrates always contain these elements in a proportion of one carbon atom, to two hydrogen atoms, to one oxygen atom. Think of it this way. All carbohydrate molecules will always have an equal number of carbon and oxygen atoms and will also always have twice as many hydrogen atoms. So why are carbohydrates important? Carbohydrates are the main fuel source from which all living things get their energy, but carbohydrates don't always have the same overall structure. They are classified as either simple or complex based on their chemical structure. All simple carbohydrates are sugars, referred to as saccharides. A saccharide can be made of one sugar molecule, called a monosaccharide, or two sugar molecules, called a disaccharide. An example of a monosaccharide is the sugar glucose. It's a monosaccharide because it's made of a single sugar molecule. Simple sugars like glucose are the quickest form of energy because your cells can break them down easily. Words ending in O-S-E or OSE are typically sugars, such as the monosaccharides fructose, galactose, and dextrose. Like glucose, these monosaccharides are all simple sugars because they are made up of a single sugar molecule. When glucose and fructose are chemically bonded together, we get a disaccharide called sucrose, commonly known as table sugar. Sucrose is a disaccharide because it's made up of two monosaccharides. Like monosaccharides, disaccharides such as sucrose also end in O-S-E because they're sugar molecules. Now let's talk about complex carbohydrates, also known as polysaccharides. Polysaccharides are very long chains of multiple monosaccharides chemically bonded together. An entire polysaccharide is referred to as a polymer, while each individual monosaccharide in this long chain is referred to as a monomer. Examples of polysaccharides include cellulose, starches, and glycogen. Cellulose is found in all plants. It's a structural carbohydrate that is found in the cell wall of every plant cell. Starches are found in many of the foods we eat, such as potatoes and corn. Starches are also found in grains such as wheat and rice. The body's digestive system breaks down starches into glucose molecules to fuel the activities of all of our cells. Extra glucose molecules that the body doesn't immediately need for energy are stored as polysaccharides called glycogen either in the liver or in skeletal muscles. To sum up, carbohydrates are organic macromolecules containing carbon, hydrogen, and oxygen in a one to two to one proportion. Carbohydrates are the main source of energy in living organisms. Carbohydrate monomers are simple sugars called monosaccharides. Disaccharides are two monosaccharides bonded together. Monosaccharide and disaccharide names typically end in OSE such as glucose, fructose, and sucrose. Carbohydrate polymers are called polysaccharides. Polysaccharides include cellulose, starches, and glycogen. [music]
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