Fructose and other less well known sugars are ketones. Thus, there are glucose, galactose, sucrose, and many other ‘-oses’.Other descriptive nomenclature involves use of a prefix that tells how many carbons the sugar contains.On the basis of the number of forming units, three major classes of carbohydrates can be defined: monosaccharides, oligosaccharides and polysaccharides.Tags: 2000 Solved Problems In Discrete MathematicsX By Lois Gould EssayQuickbooks Business PlanEssay On Diwali Festival ForPhd Thesis On Economics Of EducationStarting A Clothing Boutique Business PlanBernard Marx Brave New World EssayEssay Title Page OutlinePersonal Statement Conclusion ParagraphParenthetical References In Research Papers
Carbohydrates, also called Carbs, are defined as aldehydic or ketonic compounds with a some number of oxydrilic groups (so polyhydroxy aldehydes or ketones as well).
Many of them, but not all, have general formula (CH4 are considered carbohydrates); some, in addition to carbon (C), oxygen (O) and hydrogen (H), include nitrogen or sulfur.
Two sugars having the same chemical form (aldoses, for example) and the same number of carbons, but that differ only in the stereochemical orientations of their carbons are referred to as diastereomers (Figure 2.149).
For example, glucose, galactose, and mannose all have the formula of C6H12O6, but are chemically distinct from each other in the orientation of hydroxyl groups around the carbons within them.
The list that follows gives the common sugars and their descriptors.
•Ribose = aldo-pentose •Glucose = aldo-hexose •Galactose = aldo-hexose •Mannose = aldo-hexose •Fructose = keto-hexose Diastereomers Figure 2.149 - Diastereomers Sugars may have multiple asymmetric carbons and thus differ from each other in the configuration of hydroxyl groups on asymmetric carbons.Figure 2.148 - Common sugar structures Monosaccharides The most common monosaccharides include glucose, fructose, galactose, ribose, and mannose.Of these sugars, all but one (fructose) exists as an aldehyde. By convention, the letters ‘ose’ at the end of a biochemical name flags a molecule as a sugar.People of some cultures eat food with very little carbohydrates, but they still remain healthy.Research in the United States and Canada have shown that people get about 40% to 60% of their energy from carbohydrates.Some foods have high levels of carbohydrates including bread, pasta, potatoes, cereals, rice etc.Carbohydrates, together with lipids, proteins and nucleic acids, are one of the four major classes of biologically essential organic molecules found in all living organisms. Figure 2.150 - Epimers - D-Galactose and D-Glucose differ only in the configuration of carbon #4 Enantiomers and epimers Figure 2.151 - Enantiomers - D-Glucose (left) and L-Glucose (right) are mirror If two sugars are identical except for having one hydroxyl configured differently (such as images glucose and galactose - Figure 2.150), they are diastereomers known as epimers.If the configuration of all of the hydroxyls of one sugar is exactly the opposite of their configuration in another sugar, the two sugars are mirror images of each other (Figure 2.151). Please note that due to the way sugars are named, L-glucose is the mirror image of Dglucose. Certain carbohydrates are an important storage and transport form of energy in most organisms, including plants and animals.There are four types of carbohydrates, named by the number of sugar molecules they contain.