Carbohydrates are naturally occuring polyhydroxyaldehydes or polyhydroxyketones, or they are compounds that react with water to give these compounds. They include sugars, starches, cellulose, and similar substances.
Monosaccharides
Carbohydrates that are unable to react with water and usually are the units making up larger carbohydrates are called monosaccharides. The most common is glucose, a pentahydroxyaldehyde, and it is the most widely occuring structural unit in the entire living world. It is the builing unit for many important polysaccarides such as cellulose and starch. Fructose, a pentahydroxylketone, is another monosaccharide that makes sugar (sucrose) when combined with glucose.
CH2-CH-CH-CH-CH-CHO | | | | | OH OH OH OH OH glucose (open-chain form) CH2-CH-CH-CH-CO-CH2 | | | | | OH OH OH OH OH fructose (open-chain form) The open-chain forms account for less than 0.1% of all the molecules. Monosaccharides usually come in cyclic forms.
Carbohydrates that are unable to react with water and usually are the units making up larger carbohydrates are called monosaccharides. The most common is glucose, a pentahydroxyaldehyde, and it is the most widely occuring structural unit in the entire living world. It is the builing unit for many important polysaccarides such as cellulose and starch. Fructose, a pentahydroxylketone, is another monosaccharide that makes sugar (sucrose) when combined with glucose.
CH2-CH-CH-CH-CH-CHO | | | | | OH OH OH OH OH glucose (open-chain form) CH2-CH-CH-CH-CO-CH2 | | | | | OH OH OH OH OH fructose (open-chain form) The open-chain forms account for less than 0.1% of all the molecules. Monosaccharides usually come in cyclic forms.
ليست هناك تعليقات:
إرسال تعليق