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My AP Biology Thoughts
Unit 1 Episode #42
Welcome to My AP Biology Thoughts podcast, my name is Adrienne and I am your host for episode #42 called Unit 1 The Chemistry of Life: Carbohydrate Structure, Function, & Examples. Today we will be discussing the functional groups found in carbohydrates, the different types and functions as well as examples of carbohydrates.
Segment 1: Introduction to Carbohydrate Structure, Function, & Examples
- To start off, let me explain what a carbohydrate is. A carbohydrate is one of the four major classes of macromolecules along with lipids, proteins, and nucleic acids. It consists of carbon, hydrogen, and oxygen in a 1 to 2 to 1 ratio and you might have seen variations of its chemical formula like C6H12O6. Carbohydrates have two major functional groups that are clusters of atoms with certain properties and functions. The first functional group are hydroxyls or alcohols that contain an oxygen atom bonded to a hydrogen atom. Through dehydration synthesis, they form an ether bond which is when an oxygen atom is bonded to two alkyl or aryl groups so in this case, two carbon chains. The other group are carbonyls which contain aldehydes and ketones. The main difference between the two is the positioning of the carbonyl group where aldehydes have a carbon atom bonded to a hydrogen atom and a hydrocarbon group while ketones are bonded to two hydrocarbon groups.
- Carbohydrates also have four different types which are monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides are the smallest type of carbohydrate and contain 1 sugar molecule as the prefix suggests. Disaccharides contain 2 sugar molecules while oligosaccharides are polymers that contain 3-9 sugars and lastly, polysaccharides have 10 or more sugars. Regardless of the type of carbohydrate, they contain chains of hydrocarbons that form a hexagon shaped structure.
- Moving onto the functions of carbohydrates, one of them is that they are sugars which act as a source for energy. Since most cells prefer glucose as their source of energy, carbohydrates are vital to carry out basic functions. Carbohydrates also act as energy storage when the body already has enough energy to support its functions. Later once the body uses up its immediate source of energy, carbohydrates like glycogen are broken down. Furthermore, glucose is converted to ribose and deoxyribose, which are components of nucleic acids like DNA and RNA. They also tie into amino acids because they are substrates that interact with enzymes during chemical reactions.
Segment 2: Example of Carbohydrate Structure & Function
- To illustrate carbohydrates in real life, examples of monosaccharides include glucose, fructose, and galactose. Although they have the same chemical formula, they differ in the structural orientation of the carbon atoms. As for disaccharides, three examples include sucrose, which is table sugar, lactose, which is the sugar found in milk, and maltose, which is created in seeds and other parts of plants. Again, they share the same formula but differ in the types of monosaccharides that they contain. However, it’s important to note that glucose is the commonality between all carbohydrate polymers because it’s a part of every disaccharide, oligosaccharide, and polysaccharide. For oligosaccharides, examples include raffinose and stachyose while examples for polysaccharides include glycogen, cellulose, starch. These 3 polysaccharides tie into the functions of carbohydrates that I discussed earlier where glycogen is the main energy storage in animals and is stored in the liver and muscles, cellulose creates the rigid, structure of plant cell walls, and starch is the main energy storage in plants. As for energy sources, an example is the human brain which only uses glucose to produce energy and function. This is why we feel light headed if we haven’t had food or sugar for an extended amount of time.
Segment 3: Digging Deeper Carbohydrate Structure, Function, & Examples
- To dig deeper into carbohydrates and its connection to the chemistry of life, it shares two similar processes with the other macromolecules which are dehydration synthesis and hydrolysis. In dehydration synthesis, polymers are created from monomers by taking water out and forming covalent bonds between the monomers. Specifically for carbohydrates, it forms a glycosidic linkage. For example, when forming sucrose, the alcohol group from glucose reacts with the anomeric carbon from fructose and forms an ether bond. In hydrolysis, the opposite occurs where water is used to break the bonds in polymers and convert it to monomers. For example, animals break down glycogen into glucose when they are fasting in order to obtain energy and maintain homeostasis. Another concept it ties into is polarity which is the distribution of electrical charge in atoms and determines how atoms share their electrons and interact with other molecules. Carbohydrates are polar which means they are soluble in water. However, their solubility decreases as they become bigger so monosaccharides are very soluble but polysaccharides are not. For example, carbohydrate’s polar properties are seen in sucrose because it dissolves easily in water which is due to the attraction between the hydrogen bonds of water and the dipole-dipole interactions of sucrose. So that about sums up carbohydrates and its relevance to the chemistry of life.
Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!
Music Credits:
- “Ice Flow” Kevin MacLeod (incompetech.com)
- Licensed under Creative Commons: By Attribution 4.0 License
- http://creativecommons.org/licenses/by/4.0/
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