BIOC 2580 Lecture Notes - Lecture 2: Starch, Galactose, Glycosidic Bond
1 Dec 2016
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Document Summary
Sugars are the most abundant biomolecule on earth. Number of possible sugar molecules are very large: unlike proteins. Monosaccharides (simple sugars: consist of a single sugar molecule - glucose. Oligosaccharides: short chains of monosaccharide units, disaccharide = 2 sugar units sucrose. Polysaccharides: polymers of 20 or more sugar units glycogen and cellulose. Monosaccharide combines two organic functional groups: they have a carbonyl c=o group, which is either an aldehyde or a ketone. Have at least 2 carbons bearing hydroxyl (alcohol) groups. So, sugars are either polyhydroxy aldehydes or polyhydroxy ketones. The chemical properties of sugars reflect the properties of alcohols and ketones/aldehydes. Monosaccharaides are very soluble in water and poorly soluble or insoluble in organic solvents like ether or hexane: colorless, sweet, (ch2o)n. Simplest monosaccharides contain 3 carbon atoms (trioses) 3 carbon atoms = 1 carbonyl group and two carbons bearing hydroxyl groups. Two trioses: aldose glyceraldehyde, ketose dihydroxyacetone.
