Carbohydrates

• Carbohydrates are classified as monosaccharides, disaccharides, and polysaccharides
• Monosaccharides are carbohydrates that consist of only a single monomer
• Trioses, tetrose, pentose, and hexose sugars are examples of monosaccharides based on the number of carbons they possess
• A triose sugar like glyceraldehyde has a chain with three carbon atoms and is used in nutrition
• Tetroses like erythrose have a chain with four carbon atoms and are found in human blood and cartilage tissues
• Pentoses like ribose and deoxyribose have a chain with five carbon atoms
• All carbons in a monosaccharide are bonded to a hydroxyl group (-OH) except for one which is bonded to a carbonyl group (C=O)
• Monosaccharides can be aldoses or ketoses, with aldoses being aldehyde sugars and ketoses being ketone sugars
• Glucose is an aldohexose, a form of sugar mostly transported through the circulatory systems of animals
• Fructose is a ketohexose found in green plants, fruits, and honey, tasting sweeter than sucrose
• Sucrose is a disaccharide composed of fructose and glucose, transported in plants from leaves to other parts of the plant
• Sucrose is a disaccharide composed of glucose and fructose
• Sucrose is broken down by the carbohydrate-digesting enzyme sucrase in the small intestines to release glucose and fructose molecules
• Lactose is a disaccharide composed of galactose and glucose, found in milk and broken down by the enzyme lactase
• Maltose is a disaccharide composed of two glucose molecules, found in germinating seeds of cereal plants and used in the manufacture of beer
• Oligosaccharides are products of condensation of 3 to 10 monosaccharides, examples include raffinose and fructooligosaccharide
• Polysaccharides are polymers made up of many monosaccharide subunits linked by condensation reaction, examples include starch, glycogen, cellulose, and chitin
• Starch is a polysaccharide consisting of α glucose monomers linked by condensation reaction, found in grains and tubers
• Starch has two variants: amylose, made up of unbranched chains of glucose, and amylopectin, made up of highly branched chains due to 1,4 and 1,6 glycosidic bonds
• Starch serves as a glucose storage molecule and can be hydrolyzed to release glucose when needed
• Glycogen has more branches and is less dense and more soluble than plant starch
• Insulin converts excess glucose into glycogen and is produced by the pancreas
• Cellulose is a structural polymer found in plant cells, composed of long unbranched chains of ß-glucose molecules
• Cellulose cannot be digested by humans due to the 1,4-glycosidic bonds, but can be broken down by organisms possessing cellulase enzymes to release glucose
• Chitin is a structural polysaccharide found in arthropods and fungi, made up of acetylglucosamine molecules
• Nearly all processes necessary for life depend on a set of organic molecules including carbohydrates, proteins, lipids, and nucleic acids
• Organic compounds are based on the element carbon, forming the framework of all biological molecules
• Macromolecules or polymers are large forms of organic compounds, like carbohydrates polymers such as starch, cellulose, and glycogen
• Polysaccharides are polymers of simple sugars (monosaccharides)
• Carbohydrates are organic molecules widely distributed in animals and plants, containing carbon, hydrogen, and oxygen
• Carbohydrates are classified into monosaccharides, disaccharides, oligosaccharides, and polysaccharides
• Monosaccharides cannot be broken down into simpler compounds and are classified based on the number of carbon atoms they possess
• Trioses, a type of monosaccharide, have a chain with three carbon atoms, like glyceraldehyde
• Tetroses, another type of monosaccharide, have a chain with four carbon atoms, like erythrose
• Pentoses, with five carbon atoms, include ribose and deoxyribose, found in RNA and DNA respectively
• Hexoses, with six carbon atoms, include glucose and fructose
• Monosaccharides are described by the formula (CH2O)n, with a ratio of 1:2:1 for C:H:O
• Physiologically important monosaccharides include arabinose, deoxyribose, ribose, fructose, glucose, galactose, and mannose
• Glucose is the main metabolic fuel for mammals and is the main form of sugar transported through circulatory systems
• Fructose, a ketohexose, is found in green plants, fruits, and honey, and is sweeter than sucrose