Glycosides are formed by replacement of the anomeric hydroxyl group by some other moeity (the anomeric carbon represents the carbonyl carbon in the sugar's straight chain form, which holds a hydroxyl group after hemi-acetal formation). Let's practice using 'glycoside' in a sentence: Nucleosides are glycosides of ribose or deoxyribose where the hydroxyl group has been replaced by a nitrogen containing base. Nucleotides such as GTP, CTP, TTP, and ATP are phosphorylated nucleosides. This is an important bit of MCAT vocabulary. (Nucleotides are not the only instance of phosphorylated sugars by any means. Phosphorylated sugars are important intermediates in the metabolic pathways of respiration, including glucose 6-phosphate, glyceraldehyde 3-phosphate, and dihydroxyacetone phosphate.)